WADC TECHNICAL REPORT 58-110 ENGINEERING RESEARCH INSTITUTE THE UNIVERSITY OF MICHIGAN ANN ARBOR Final Report DETERMINATION OF THE SOUND TRANSMISSION CHARACTERISTICS OF VARIOUS AIRCRAFT SOUNDPROOFING MATERIALS SO So Kushner J. C. Johnson Supervisor, Acoustics Laboratory ERI. Prject 2490 WRIGHT AIR DEVELOPMENT CENTER, U. S. AIR FORCE CONTRACT NO. AF 33(616)-3435' PROJECT NO. 1370, TASK NO. 13465 WRIGHT-PATTERSON AIR FORCE BASE,' OHIO January 1958

FOREWORD The experimental program was initiated under the direction of R. N. Hamme* and was concluded under the direction of Jo Co Johnson, Project Supervisor. The author wishes to acknowledge the advice and assistance rendered by N. E. Barnett and H. F. Reiher* and to make note of the technical assistance of W. O0 Bailey, Go Eberle.,* and R. Kriewall.** The data reduction and the drafting were accomplished by Wo 0o Bailey and M. Eo Kirchoff, with the secretarial serve ice provided by Mrs. Ao Do Simmso The work was sponsored by the Wright Air Development Center, U. S. Air Foroeo This report covers work performed under Contract No. AF 33(616)-3435, Project No. 1370, Aeroelasticity, Vibration, and Noise, Task No. 13465, "Standardization of Soundproofing Blankets." Mr. Joseph Ro Bengoechea of the Dynamics Branch, Aircraft Laboratory, acted as task engineer. Now with Geiger and Hamme, Consultants in Acoustics, Ann Arbor, Michigan. **Now with the Uo So NavyO WADC TR 58-110

ABSTRACT Determination of the sound transmission characteristics for various aircraft fuselage acoustic treatments was accomplished utilizing a small sample transmission-loss apparatus. The materials tested were ranked in relation to the theoretical weight-law attenuation of a 0.020-inch-thick dural panel. PUBLICATION REVIEW This report has been reviewed and is approved. FOR THE COMMANDER: RANDALL D. KEATOR Colonel, USAF Chief, Aircraft Laboratory Directorate of Laboratories WADC TR 58-110 iii

TABLE OF CONTENTS Page ABSTRACT iii LIST OF ILLUSTRATIONS v INTRODUCTION 1 EXPERIMENTAL APPARATUS AND PROCEDURE 1 Apparatus 1 Procedure 2 PRESENTATION OF DATA 2 SUMMARY OF RESULTS CONCLUSIONS 3 WADC TR 58-110 iv

LIST OF ILLUSTRATIONS* Figure Page 1 Aircraft Transmission-Loss Test Apparatus. 9 2 Instrumentation for Aircraft Transmission-Loss Test Apparatus. 10 3 - 26 Theoretical and Experimental Transmission Loss for Structures Nos, 1 - 24. 11 - 34 Table I Description of Soundproofing Structures 5 II Summary of Transmission-Loss Characteristics According to Structure Number 7 III Summary of Transmission-Loss Characteristics of Similar Treatment Configurations. 8 *See Table I. WADC TR 58 110 v

INTRODUCTION This report covers the work done under Contract No. AF 33(616)-3435 between Wright Air Development Center and The University of Michigan, and in general follows the principles of experimentation presented in two previous reports, namely, "Report on Sound Transmission Through Aircraft Wall Structures," P. H. Geiger, R. N. Hamme, Contract W33038 ac-14775, November 10, 1947, and "Sound Transmission Through Aircraft Soundproofing Structures," P. Ho Geiger, R. N. Hamme, Contract AF 33(038)-2652, October 27, 1949. Thus only a brief description of the apparatus and the procedure is presented in this report. The types of materials tested under this contract include acoustical tapes, plastic-back blankets, polyurethane sheets, and various honeycomb configurations. The results obtained using these materials are tabulated in the Summary of Results. EXPERIMENTAL APPARATUS AND PROCEDURE APPARATUS Essentially, the transmission testing apparatus, as shown in Figure 1, consists of two separate enclosures. One is an acoustically live source chamber and the second, a highly absorbent or anechoic termination. The source chamber consists of a 30-inch concrete cube through which a 17.5-inch square hollow traverses. For access purposes one end of the hollow is blocked by a securely bolted 0.25inch steel plate. The acoustic source consists of a bank of sixteen seriesparallel 4-inch dynamic speakers mounted on a single frame for sound excitation in the range from 58 cps through 2700 cps. In addition twin tweeters are used to provide a reliable source from 2890 cps through 8800 cps. A crystal microphone (A) is used to monitor the sound pressure level in the source chamber. The termination closure is composed of a tube 18.5 inches square and 8 feet long closed at one end and packed with a sound-absorbing material. An acoustic pickup (B) is located at the face of the open end. The make-up of the linking structure between the two enclosures is largely determined by the material to be tested. The open end of the source chamber is framed by a 0.25-inch steel section, The 0.020-inch-thick dural standard is then mounted over the opening and held in place by smooth-surfaced one-inch steel bars bolted into place. Four studs, one at each corner, are imbedded in the concrete bordering the open face of the source chamber. Over these studs are placed the appropriate wooden spacer frames and the Manuscript released by the author 31 January 1958 for publication as a WADC Technical Report. WADC TR 58-110 1

sample. The trim cloth then covers the sample face and the termination is butted against the sample. The instrumentation consists of the source-drive electronics and the termination-response analysis system. The source drive is provided by a warble oscillator, the center frequency of which is set to the desired value with the aid of an oscilloscope and a secondary-standard oscillator. The output of the warble oscillator is then amplified, monitored, and applied to the speaker system. The analysis system is used to measure the relative sound pressure levels existing in the source and termination enclosures. The signal from A or B (see Figure 1) is fed successively through a preamplifier, intermediate amplifier, filter, and final amplifier. The final output is then read from a db meter and can be monitored aurally. PROCEDURE The 0.020-inch dural panel is first securely attached at the opening of the source chamber. The termination enclosure is sealed to the source chamber and calibration data (A-B) is then obtained for the panel. Next, appropriate spacer frames are added to the face of the source chamber in order that a 3-inch space be maintained between the dural panel and the outside face of the treatment, except for the acoustic tapes which were applied directly to the 0.020-inch dural panel. After securing the termination enclosure, transmission-loss data are obtained for the combination of the dural panel and the treatment (B-A). PRESENTATION OF DATA Since twenty-four separate acoustic treatments were tested, it was decided to assign a reference structure number to each treatment to avoid confusion. The descriptive information is shown in Table I where the composition of each structure is described and assigned both a structure number and a figure number, the latter being a key to the graphic presentation of the transmission-loss data obtained for the accompanying structure. In these figures (3-26) two sets of data are plotted. The straight line represents the theoretical weight-law attenuation for total treatment including the dural panel, while the broken line represents the algebraic sum of the transmission-loss values observed for the sample and the theoretical attenuation values of the dural standard. Thus, the difference between these curves indicates the actual transmission loss contributed by the treatment itself. This data presentation is consistent with that of the two previous reports. WADC TR 58-110 2

SUMMARY OF RESULTS It must be noted that transmission-loss data for the various configurations tested are of a relative nature and are presumed to differ from absolute values by a certain constant which is, as yet, undetermined. This is true except for the honeycomb structures, which upon their introduction into the testing system result in a change in the system from a basic single-wall structure to an enigmatic double-wall configuration. Therefore no positive correlation of data is anticipated between the transmission-loss results obtained for the honeycomb structures and those obtained for the tapes, polyurethane sheets, and quilted blankets, using the present transmission-loss apparatus. Besides the transmission-loss data shown in Figures 3-26, several additional transmission characteristics for the materials tested have been computed. Average attenuation for the Merit-Factor range of 2890-8800 cps and for the Q range 1830-5400 cps have been computed for each test and are presented at the base of each attenuation figure. Furthermore, the data are compared with theoretical weight-law attenuation values at 5000 cps and 3000 cps, which are the midpoint frequencies of the Merit Factor and the Q Factor ranges, respectively. In addition, the Merit Factor and the Q Factor have been determined for each sample, thus taking into account the importance of the treatment weight in selecting an efficient soundproofing structure. These factors may be defined as follows: db average attenuation 2890-8800 cps Merit Factor = better than weight law at 5000 cps treatment weight db attenuation 1830-5400 cps better Q Factor = than weight law at 3000 cps treatment weight The foregoing data are summarized in Tables II and III. Table II lists the data computed for each structure in sequence according to the structure number, while Table III groups the transmission-loss characteristics of each class of structures according to their treatment weight. CONCLUSIONS As has been stated previously, there is no valid correlation between the honeycomb structures and the various other configurations tested. However, if a similarity in the test configuration can be construed to permit valid comparison of transmission-loss data for similar structural materials, then the data obtained for the honeycomb panels may be evaluated, one against another. From Table III it can be seen that, with an increase in the thickness of the honeycomb panel, WADC TR 58-110 3

there is a general decrease in the value for the average attenuations in the Merit and Q Factor ranges minus the appropriate theoretical weight-law attenuation values. This means that for these frequencies the panels become relatively less efficient with increasing weight and thickness. This is also shown by the computed Merit and Q Factors. That this should be the case is indeed a matter of conjecture, and emphasizes once again the inherent value of a testing program yielding absolute transmission-loss data. Of the other structures and materials tested, both the polyurethane and quilted-insulation blankets demonstrate larger db-better-than-weight-law values in the Merit and Q Factor ranges than do the tapes. This is shown also by the relatively large Merit and Q Factors obtained from both the polyurethane and blanket data; the polyurethane structures show a predominance of efficiency in these frequency rangeso The tests reported above discriminate against displaying the important attribute of acoustic tapes, which is to provide supplementary vibration damping to the treated structure. In panel transmission measurements, a treatment which provides damping inhibits excessive transmission at frequencies corresponding to the natural resonances of the panel, the transmission loss at these frequencies approaching theoretical weight-law values in the limit with increased damping. However, the bare dural panel in the present transmission apparatus does not exhibit any pronounced resonance phenomena within the test-frequency range, and consequently, the only important remaining effect of a damping-tape treatment is an increase in the effective weight of the panel. For example, a comparison of structures Nos. 1 and 2 shows that the average increase in attenuation due to three additional layers of tape is 5.0 and 5.1 db, respectively, for the 28908800 cps and the 1830-5400 cps ranges. The theoretical increase in attenuation to be expected from the increased effective weight of the panel amounts to 5.4 db.o The poor Merit and Q Factor values yielded by the acoustic-tape treatments is the result of the nonapplicability of this measure for the effectiveness of damping treatments. WADC TR 58-110 4

TABLE I DESCRIPTION OF SOUNDPROOFING STRUCTURES Structure Composition* Figure Noo Reference 1 Acoustimat Tape, 1 thickness 3 2 Acoustimat Tape, 4 thicknesses 4 3 Minnesota Mining Aluminum Tape 36PSL152311L82, 4 thicknesses 5 4 Polyurethane, 1/8-inch thickness 6 5 Polyurethane, 1/4-inch thickness 7 6 Polyurethane, 3/8-inch thickness 8 7 Acoustimat Tape, 4 thicknesses, plus polyurethane, 1/8-inch thickness 9 8 Acoustimat Tape, 4 thicknesses, plus polyurethane, 3/8-inch thickness 10 9 Insulation Blanket, Quilted, 5640-269-9388, 3/8-inch thickness, Type I 11 10 Insulation Blanket, Quilted, 5640-269-1179, 1/4-inch thickness, Type II 12 11 Insulation Blanket, Quilted, 5640-269-1049, 1/4-inch thickness, Type II 13 12 Honeycomb panel, cotton core, 7/16-inch cell size, 0.016-inch dural skin, 3/8-inch thickness 14 13 Honeycomb panel, cotton core, 7/16-inch cell size, 0.016-inch dural skin, 1/2-inch thickness 15 14 Honeycomb panel, cotton core, 7/16-inch cell size, 0.016-inch dural skin, 1-inch thickness 16 *All include O0020-inch dural panel~ WADC TR 58-110 5

TABLE I (concluded) Structure Composition* Figure No Reference 15 Honeycomb panel, cotton core, 7/16-inch cell size, 0.020-inch dural skin, 3/8-inch thickness 17 16 Honeycomb panel, cotton core, 7/16-inch cell size, 0.020-inch dural skin, 1/2-inch thickness 18 17 Honeycomb panel, cotton core, 7/16-inch cell size, 0.020-inch dural skin, 1-inch thickness 19 18 Honeycomb panel, cotton core, 7/16-inch cell size, 0.025-inch dural skin, 3/8-inch thickness 20 19 Honeycomb panel, cotton core, 7/16-inch cell size, 0.025-inch dural skin, 1/2-inch thickness 21 20 Honeycomb panel, cotton core, 7/16-inch cell size, 0.025-inch dural skin, 1-inch thickness 22 21 Honeycomb panel, fiberglass core, 1/4-inch cell size, 0.016-inch dural skin, 1-inch thickness 23 22 Honeycomb panel, fiberglass core, 1/4-inch cell size, 0.020-inch dural skin, 1-inch thickness 24 23 Honeycomb panel, fiberglass core, 1/4-inch cell size, 0.025-inch dural skin, 1-inch thickness 25 24 Honeycomb panel, metal core, 1/2-inch thickness 26 *All include 0.020-inch dural panel. WADC TR 58-110 6

TABLE II SUMMARY OF TRANSMI[SSION-LOSS CHARACTERISTICS ACCORDING TO STRUCTURE NUMBER db Better Than @ Structure* Total Treat. 2890-8800 cps 1830-5400 cps Merit Q Weight Law H Weight Weight Av. Att. Wt. Law Av. Att. Wt. Law Factor Factor Ul iJ ii i..,MF Ran, Range 0 1 0.4385 0.1585 44.4 44.1 40.0 39.6 1.89 2.31 0.3 0.4 2 0.7819 0.5019 49.4 49.1 45.1 44.7 0.56 0.84 0.3 004 3 0.7472 0.4672 52.8 48.7 48.1 44.3 8.78 8 13 4.1 3.8 4 0 3616 o.0816 50.3 42.4 44.8 38.0 96.3 84.1 7.9 6.8 5 0.3982 0.1182 54.8 43.3 47.6 38.8 97.4 73.7 11.5 8~ 8 6 0.4217 0.1417 59.8 43.7 53.8 39.3 113.0 102.0 16.1 14.5 7 0.8194 0.5394 56.4 49.5 51.5 45.1 12.8 11.9 6.9 604 8 0.8795 0-5995 67.7 50.1 60.9 45.7 29.2 25.4 17.6 15o 2 9 0.5106 0.2306 64.2 45.4 56.6 41.0 81,5 67,6 18.8 15.6 10 0.5257 0.2457 63.7 45.7 58.0 41.2 7353 68.4 18.0 16.8 11 0.4592 0.1792 61.9 44.5 53.9 40.1 97.1 77.0 17.4 13.8 12 1.1119 0o8319 6302 52.2 60.4 47.7 13.2 15o3 110 127 13 1,2519 0.9719 63,8 53.2 59.3 48.6 10,9 11.0 10.6 10.7 14 1.5019 1.2219 64.6 54.8 60.5 50~3 8~02 8.35 9.8 10.2 15 1.2769 0.9969 64.8 53.4 61.7 48.9 11.4 12.8 11.4 12.8 16 1.2899 1.0099 64.7 53.4 60.6 49.0 11,2 11.5 11.3 11.6 17 1.5899 1.3099 63.9 55.3 59 5 50.8 6.57 6.64 8.6 8.7 18 1.4339 1.1539 65.7 54.4 63.6 49.9 9.79 11.9 11.3 13.7 19 1.4619 1.1819 64.7 54.8 60.9 50,3 8.38 8-497 9.9 10.6 20 1.7119 1.4319 64.5 55.9 59.3 51.5 6.01 5.45 8.6 7o8 21 1.4169 1.1369 62.5 54.3 58.0 49.8 7.21 7.21 8.2 8,2 22 1.5099 1.2299 66 o0 548 60.1 50.4 7.42 6.42 11.2 9.7 23 1.6269 1,3469 66.1 55.5 59.8 51.1 7.87 6.46 10o6 8.7 24 1.5169 1.2369 66.6 54-9 62.9 50.5 9.46 10.0 11.7 12o4 *See Table I.

TABLE I II SUMMARY OF TRAINSMISSITON-LOSS CHARACTERISTICS OF SIMILAR TREATMENT COI\NFIGURATIONS,3.db Better Than Structure* Treat. 2890o8800 cps 1830-5400 cps Merit Q Structup Weight... We ight Av. Att. Wt. Law Av. Att. Wt. Law Factor Factor co... MF Range Q Range Tapes 1 0o.1585 44.4 44.1 40.0 39.6 1.89 2o31 0.3 0.4 3 0.4672 52.8 48.7 48.1 44.3 8.87 8,13 4.1 3 2 0.5019 49.4 49.1 45.1 44.7 0.56 0.84 0.03 04 Polyurethane 4 0.0816 50.3 42.4 44.8 380o 96.3 84.1ol 7.9 6~8 5 0.1182 54.8 43.3 47.6 38.8 97.4 73.7 115 8.8 6 0.1417 59.8 43 7 53.8 39.3 113 102 16.14o 5 Tape plus Polyurethane 0.5394 56o4 49.5 51.5 45.1 12.8 11.9 6.9 6.4 8 0.5995 67.7 50.1 60.9 45~7 29.2 25.4 17.6 15.2 Insulation Blankets, Quilted OD 11 0.1792 61.9 44.5 53~9 40.1 971 77.0 17138 9 0.2306 64.2 45.4 56.6 41.0 81.5 67.6 18.8 15.6 10 0.2457 63.7 45.7 58.o 0 41.2 73.3 684 18.0 16 8 Honeycomb Panels, 3/8-inch Thickness 12 0.8319 63.2 52.2 60.4 47.7 13.2 15.3 11.o 12.7 15 0.9969 64.8 53.4 61.7 48.9 11.4 12.8 11.4 12.8 18 1.1539 65.7 54.4 63.6 49.9 9'79 11.9 11. 3 13o7 Honeycomb Panels, l/2-inch Thickness 13 0.9719 63.8 53.2 59.3 48.6 10.9 11.0 10.6 10.7 16 1.0099 64.7 53.4 60.6 490 l o 11.2 1135 11.6 19 1.1819 64.7 54.8 60.9 50.3 8.38 8.97 9.9 10.6 24 1.2369 66.6 54.9 62.9 50-5 9.46 10o0 11.7 12.4 Honeycomb Panels, 1-inch Thickness 21 1.1369 62.5 54.3 58.o0 49.8 7.21 7.21 8.2 8o2 14 1.2219 64.6 54.8 60o. 50.3 8.02 8.35 9.8 10.2 22 1.2299 66o0 54.8 60.1 50o4 7o42 6.42 112 97 17 1.3099 63.9 5553 5995 0o.8 6.57 6.64 8.6 8,7 23 1.3469 66.1 55.5 59.8 51.1 7.87 6.46 10.6 8.7 20 1.4319 64.5 55~9 5953 51.5 6.01 5.45 8.6 7.8 *See Table I.

a,1 SPEAKER DRIVE INPUT I 0~~o. 24" 3 DU' - AL o TWEETER DRIVE INPUT TRIM CLOTH TWEETER DRIVE INPUT TRIM CLOTH FIGURE I. AIRCRAFT TRANSMISSION-LOSS TEST APPARATUS

H. P. AUDIO DUMONT CRO WARBLE 6L6 HEATKIT OSCILLATOR SERIAL NO. 3575 OSCILLATOR AMPLIFIER AC VTVM PROP. NO.244 4 OHM OUTPU TO SPEAKER AND TWEETER DRIVES A tB TRIMM INTERMEDIATE FINAL PROFESSIONAL PREAMPLIFIER FILTER PEMLFEAMPLIFIER AMPLIFIER EARPHONES AND METER FIGURE 2. INSTRUMENTATION FOR AIRCRAFT TRANSMISSION -LOSS TEST APPARATUS

SOUND TRANSMISSION CURVE STRUCTURE I 10 20 30 D 40 Io I X I IIH IIM 1 3 0 FRQUNC I CPSl I3T L y 11 II14 60 1 g 1T i005' 7 A2 a 3 4 5 6 7 8 9 22 4 5 - 7 8 9 100 1000 10000 FREQUENCY IN CPS WADC |.020"l Dural O.2800 lb/ft2 1-. |Tape (1 Layer) 0.1144 | |4 Trim 0. 0441 Treatment Weight 0.1585 Average Attenuation, 2890-8800 cps - 44.4 Average Attenuation, 1830-5400 cps = 40,0 It ~~~ I IMerit Factor = 1.89 Hll3"-*Q Factor - 2.21 FIGURE 3 WADC TR -110 11

SOUND TRANSMISSION CURVE STRUCTURE 2 0 E II 1111 I- 111111 -- 111 1 g WX W E X4111111 Mil 1[I1tI \t la 1414k~ ~~~~~~~~~~~~~~~1 1 1 i i t 1 111.11 i..;..... =w T 111 1 III 11. f. tnil III. T | I X 1T 1 I.11 I I II.tl mtt r lvRr1 rL11111 1 1 IIIl -I I I I i It [lifllLLL IlLtIIH 10 20 30 o I 40 t _= 60 80 90 30 tl Hill8 I 57_ L _IIII I | ~lIIOIIIIIIIIIII~IIIi I I tI|III |IIIIIIIIIIIIII 1005 6 LUIU 78 3L~bL 4 5 6 78 8 4 5 8 1 00' 1000 1H000 FRQUENCY IN CPS ~0.020" Durai 0.28300 lb/ft2.Tape (!+4 L~ayers) 0.4578 Trim o. o&41 ni 111 7 T 1 11 1 [ Xs |' [it 111 li1 1iil> 1.t..~izf.....lliiiiilllllall~ Treatmenrt W'eight O.q 509 Aiverage a~ttenuation, 2890-8800 cps = 49.1 mfill Av erage Att1 enuation, 1 830 - Oc1ps = I5I1 40 l 7 i T{Eerit Fator =.56,~- 3"-~ Q Factor = O.SL FIGURE ~4 WA C TR. 8-110 12 4 0 7. FF1 1 HEIII. H ATz L LLIIlllllllllll I1 1151 ~bllXIIII z C IfilT w - XWe l I I It 1101 fil o I 1Ll 11111 uu m 1 — -W i1l1 1 I~llllll Ill~il~l 76 0 I I i I E~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~ Il fal I Il It 1 1t 80~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~fl li ml Io H ll 1111i ll I l 1l 1 1 t|i;l ig I I Ill liltFREUENCYIN CP ill limTratmrx vight 0.01 I l l xerg Att liion 110-40 cl = 5. I I I itlerI Fa1o 05 >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~l 3" I I Fato -l0l8 I Ii il ttle I IIG R 4el I 1 WADC TR 58-~~~1110ilfa IIII IH 12 t

CD l~t l E,9 +w iicO1L- -......... oo a co CY co 0 0 0 0 0 0 0 0 0 0 0 ID HI cN OII N:.LV " o9U~~~~_ NI NOIVO NU

SOUND TRANSMISSION CURVE STRUCTURE 4 0o I X S 1 I I I itfl] I If I IlWIIIII 1 litl fil II fil I 1111 30 g TlilililI lilil 1lill 1 1 1 1 I S I I I I I I I ITI! I 111TI I I IN 4 I+ 4 01 ] tlls I I 111 Il Sqlm~~~~~~~~~~~~~~~~~~~~~~~~~lE~~~~~~~~~ I Hl X l ljI[ X t Il I Hll 11111111 M 10 II I mlmi v 1IlIIIHI I lilllIrIIjItIIld3 +tH RIT 7 GT _ Tl l l'~~~~~liltl88 H 11 llllS111FTTi I 20 I -- l'~ 40 _.50 ~ Krh lilililililill I!Ri I I F lr- l IlHIIIllllllli ~ilL 1 if i IY Tl I I fill it-V l g1111m1||||||||gmil i Tt I Z ililltli { ill - l -l lb111111,119 F I I 11 —-IIIQ IT F ++g N LU~~~~~~~~~~~~~~lI 60 70 iO0 100 1000 10000 1 I FREQUENCY IN CPS L uu 1d I11 [ $ < <I I E I i I i i I Hli1I 21............... 0.020" Dural 0.2800 lb/f%2 1/8"1 Polyurethane 0,0375 " Trim O.O441 Treatment Weight O.I081 Average Attenuation, 2890-8800 cps = 50.3 Average Attenuation, 1830-5400 Cps -; 44.8 7 ll l Meri|t | tFac tor IA 96.3 Q Factor = 8.1~, C-3" -- FI GURE 6 1llWA ll mllIID C Ir T T l llR 58 -110 14 I l +1114111111 i 11111 i I I i I I I I ili1H HE~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ftH TET t T$T~~~~~~~I I II TlllT,I Ji T -11l T X+I WL11111]1I I! Ill rH il1 11 III_1,trr I I lll= I iLlLIllllr10 la IT rT 11Tt ~ lilti 1 11 I I I 1!I I = t 701 Jll l l:1 11]ll]\~~ S 11L111liuilliiil1l] too~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ll 80 IIIH I I ~ ~ ~ FREUENCYIN CP I 114 Trim 0.0441~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ii Average~~~~~~~~~~~~~ Atnaion 1 8350 Ip _w1 90 ~ ~ ~ ~ ~ ~ ei Facto -----— 3 lil Ill Q acor = 4 WADC TR 58-~~~~~~~~110 14 0 00

SOUND TRANSMISSION CURVE STRUCTURE 5 10 o Si tttISX -1 XE M W- X: 411 lt 20 30 i ZI~~~~~~~~~~~~~~I 30 I HIFFFT~F 40 50 ~ 05 0 7 B a 2 3 4 5 6 7 | 9 2 3 (4 5 6 7 8 9,> F f E 4 E g T T zH L_ H5~~ T t- ltit0i1 LL I I I I Iliiiil IlVlIL m sF o X M g t1+W I4 } INII II I i S ~-60 [i7~~~~~~~~~~~~~~~~~~~~~~~~~~iM 706 ifi4FI lTI!! 11 I 1 1 A[Ll 11j1LLI!1LlllL I I I I I IIII lIIIII i 1I t 11 1 1 L'. LL r I j I L~r 111 rl =,T _r r I | II~i flll I' i 1 1r~lTT I rl El-tI~tEL I I11I1H1 i 1I i T11v I 80 I S 100 1000 10000 FREQUENCY IN CPS, - 0.020" Dural 0 2800 lb/ ft2 I I - 5/16I" Polyurethane.O. 741 | | |< -- Trim O. 044s1 Treatment Weight O. 1182 Average Attenuation, 2890-8800 cps-_ 54.8 l ll ~~~Average Attenuation, 1830-5400 cps = 47.6 I00 I erit Factor - 97. 4 6 — 3" 4 Q Factor = 73.7 FIGURE 7 WADC TR 58-110 15

SOUND TRANSMISSION CURVE STRUCTURE 6 10I I H111 20 30 5O 6 o 70' T J (iLL l l] - - I..... I1 90 littI00 1 0 0 0 1000 FREIUENCY IN CPS 0.020" Dural 0.2800 lb/ft2 3/8"' Polyurethane O0.O976 Trim 0.0k41 Treatment Weight O..l17 Average Attenuation, 2890-8800 cps-= 59.8 Average Attenuation, 1830-5400 cps = 53.8 Mit Factor = l 2" — Il Factor - 102 FIGURE 8 WAOC TR.~-1o ~

SOUND TRANSMISSION CURVE STRUCTURE 7 10 20 30 = 40 z_ z 50 LaI ~60~ 70 a50 100 ~ ~ 7 8 9 2 3 4 5 6 7 8 9 2 3 4 ~ 6 7 8 9 100 1000 10000 FREQUENCY IN CPS 0.020" Dural 0.2800 lb/ft2 Tape (4 Layers) 0.4578 Merit Factor o 12.8 Q Factor 11l.9 1/8" Polyurethane 0.0375 Trim 0.0441 Treatment Weight 0.5394 Average Attenuation, 2890-8800 cps = 56.4 _~ 9~~ -1 Average Attenuation, 1830-5400 cps =l 1 FIGURE 9 WADC TR 58-110 17

SOUND TRANSMISSION CURVE STRUCTURE 8 10 20 0 IIIII 11111!111I S... 11 Ill — ~~~,$I~~U____,l 1 i - 111H,1i Arl X l~l -1lllimt -fill L11_I I I T ITIlII~IITl l I l i lil l ralleml; w 111 1 1 -_ _ _ _ _ _ _ I I _,, |, 1 w i lullilX~~~~~~~~~~~~~~~~telillzlsl1 _ _f _ _ IIH 30 I0 ILLII Ili 11"'"'~1 " 1 1 _ _ __' _I <1 1 _ [ l ll I II lil _ _ _ _ I I I I I I I I I I 1111I III l 20 I I30 1, H _ i 1 1 1 ===_ I! I 1 I I 1 1 1 I I! ll ill-il4i, 1011114 11111>i 211\ 1 Iiv + -t 1 -:! 1 tL tl: _ l i 1 l li ililill ilfilwl l| | I i I I | 1 1 I l l i l lb l lili l l i l lI i6,I iI I I tI I I A I II H l 420 HlrF 111111i.... 1 3 21>*Ai 11111!111 - 1111 1M11 iiliil ill, iTfi m1 11Iill II i I ItI I I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I Io f IIII H ill I I T]I I J +I I T 4II 5 0 I III_ I H I I l ^1 1 * 1,Tlf IIIII!Rl 1050. 2 30 ll 5 i 7 8 L l4E9TW A ttS ( ~ ~ ~ 0.21 ]qui[[[ lqI2l0l![[ [ —I iO0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Ml < m I 1 101101111 1000 10 fill0 FREQUENCY I I fil N Cill -I 1111111 11111111111u1r111a1 1! I 11 1|l, 0.28 0 I 11 /ft Tape (4 Layers) 0.~578 Merit Factor-= 29.2 Q Factor - 25.~' ~3/8" Polyurethane 0.097?6 ill IrTri im O, O Treatment Weight O. 5995 Average Attenuation, 2890-8800 cps = 67.7 -11" ~ P~verage Attenuation, 1830-5400 cUps = 60. 70" -.., FIGURE IO WADC R 58-:LO:L8 t 60 lil~~~~I ill _ 11 11 i 1, Ti I I I IlllllllltIlllr fll < X-111 1111111 11111 i I L L 4 X t - t II I 11I 1illllIl X [ I I I| I I I || II|||t|||!II 1 |||s|l T LL-F- 111 L I —1AI W H 1l11 uu ttm $~~~~~~~100 100 1 0 00'0llll~iI a0 +1 TmllTW llilE I I; I I 11010201 Durl 0.80 lb/ft"llljl ill s X ili:;Al~~~~ll 1: 1 01 1 0i1Tape 4 Laes 0.I I 1 4 578< l 110 W 5~ ~ ~ ~ ~vrg 6A7tenu2at4osn6 78908w cp = 6756 8 100 ~ veaeAteuto 1800540 1000060 FREQUENCY~~~ ~~ INLP

SOUND TRANSMISSION CURVE STRUCTURE 9 10 2O ~ k i I W1\ -- W = E S E j10f11 14f1 fm~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~l E2;1 11 A 20 X I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I,, I,,~~~~~~~~~ I I T I I I II - 30 IL D 40~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ z~~~~~~~~~~~~~~~~~~~~~~~~~~ I I I~~~~~~~~~~~~~~~ 40 II1 I I~~ I11 fiill ALll t S~i.illl1 ~rlt,3 }Ii1 1 T e! [~ CD,~ W IZ 11 -T I{I- I IlJL i 70 I;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 l _ i, lfrT~t Lil~tt~r |E g f 1 g' N Ttl i L l' l ililllS~l~iE _l_ I | I U II 1 l l l E l ll n rrl l lI lI AL T l I I- I ~II 70 30 I;,,,,,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I III I Hill~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 5 6 769lilltlt>. T-I 4 I 6 7 8t- 9i P, 3~l 4t~t3 5iH 6 I I I80 iF I I I M1' IA~llll! —r A I~ T i - - - -B E L I I - t;!Iii I I i H T I I II Il II m F:I. -t,:~~~~~~~f i su11l~Il f1 I t~I1t 111l ll~ lttl t 1 | 1004 11!2000:1Tiat 11> —1-3 1 4Z0000 }}Eet~ ~~~~~~~O 2"DralO280b/2 90 o I I RI~LU i III I II I-T_ I rLrUTL UJ~ ~ ~ ~ 3 8 Ilne (-38L.18871 100 FREQUENCY~~~~~~~~~~~~~~ IN P 90' 1l 111,11111I 411lilil-l L I 1r,~ < 1_ 1 t 1111111l~l -ill!lrT klSl - I _ L L1l11 T II-I11ItTUItltil 0. 02011 Dwral 0.2800 lb/fti2 3/8" Blanket (-9388) 0.1887 Trim 0.0419 Treatment Weight 0.2306 Average Attenuation, 2890-8800 cps = 64.2 Average Attenuation, 1830-5400 cps a 56.6 Merit Factor = 81.5 Q ~Factor -67.6 FIGURE I! WADC TR I8-110 19

SOUND TRANSMISSION CURVE STRUCTURE 10 I _ I 7*4k I I I t tt — +t~+_t~~L;~-~t t~it —-~ +ttt-tttcuc-c u~ 10 4~~~~~~~~~~~~~~~~ 40 o~~~~~~~~~~~~~~~~~~~~~~~~~~~~ co 70 ~L~Fl! l L~TI11L ~ ~L L L II I I I llI F[[[IF[~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I-1' 80 10056 789 2 3 4 56 7 89 Z 3 4 5 67 89 100 1000 10000 FREQUENCY INCPS 0.020" Dural 0. 2800 lb/ft2 60 I;:~~~~~~~~~~~~~~~~~~~~~~~~~y II 1/4" Blanket (-1179). 2038 Trim.I I 19 Treatment Weight O. 2h57 Average Attenuation, 2890-8800 ops - 63.7 fil~lll llli Average Attenuation, 1830-5400 cps = 58.0 1 erit Factor I 73.3 ~..3W.~.1 Q Factor = 68.4 100 5 6 7 6 9 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 FIGURE100 1000 10000 wAD~C~FREQUENCY IN C-PS 2 0.02011 Dural 0.2800 lb/ft2 1/4"'O Planket (-1179) 0e2038 Trimr oOor19 Treatment Weight 0,2457 Average Attenuationp 2890-8800 cps a 63.7 Avrerage Attenuation) 1830.5400 cpsa 5t 8.0 Merit Factor = 73.3 t3*J O~~~~~~~~~~gctor.68.k~~~~~~~~~~il

SOUND TRANSMISSION CURVE STRUCTURE I 10 rT III I I I I ~ ~ o0 11 L I 1!. 1 i MI I i 1i 1' 11 20 30 IX,,, II' 40 zIM~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i VW ILI W I;,~~~~~~ 50 --! 600 7 3 5 6 7 I 4 z0 Dural 0 lb/ft2 Zr W I 1 111 lil [IE I1 1 T1 l -1TTIII I E i I I I i l Il ll liiln~l I!TTr -qIU C-VCI~I —1 I~X~~t~''!-Ll''i Nj r"f"'ilT~ti fflX- Hiff H7 E E g g MI I X X illl I I I I I N I ff i I till IILI sn 11L I II' AI II I -I I!I I I1-T I I II 0i I ~tttt Irr r I I I I i I I I| m tfl i]r I I~ I I I fi I I I I I I I I!A~-U I I | l | |I I [ ] ~ r~i!zi |ILI LLL 1!1 111T ~ ll I'I I II l~lll slillll~ 1rlrm1:11 mTTr I I I I I 1 11elillxllll l 1 I Ill nlil lillll lll ~ tk 100 - Hs 7g 5 IFF 7 F;F 9; 2 3 4 I 6 7 I 9 2 F 3 II I1 - 4 FiF 6 7 8 9 100 1000 10000 FREQUENCY IN CPS 0.0201T Dural 0,2800 lb/ff 2 1/4" Blanket (- 1049) 0 1373 Trim o.o419 Treatment Weight 0.1792 Average Attenuation, 2890-8800 cps a 61.9 Average Attenuation, 1830-5400 cps = 53.9 Merit Factor 97.1 ~~c ~II -c Q Factor - 77.0 FIGURE 13 WA5c 8 9 28110 2:

CD CD ~~~~~~~~~~~~~~~~~I fIlll ll ll lllllllllllllll I I I IIIIIIIIIIIIIIIIm oil.......1 ~~d. -,... 1:- L.... j..:j:- illl'lL llll lll [[[i[[[[lrlllll -ii] _ _ _ _ _ _ _ i I I I I I I I I1111II__ ~~~~~~~ Ocu a ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~o CIO ME 0'-44 E-::-m,: ~ JJJJJ... t e llll-lll IIIlL Ill llJ,'.....IIL............................ 11 1.. L... D LJ c c C ( -H' ff-':~-jijj-i j!:t-Hm ei -j-;'j;j~ _j"''r il Jl~iJiJJ! iiiliiiulrttliiTT IZ1: l:TT TIT 5 I T 1111.........f E tiH........ 11111 Illrmm........ ~~YOr _:t __tg It I I )I~~~ JL J _L li c CM,r,, ]llLLJ.! I I I 11 IIII!111 1 It OIlll I I 111111L 0~~~~~~~~~~~0 _lllll IL co IIl I cmi 1lli 1C a N NOIIVN3111lllll ~ 2 l 2 11 11111IIIIIIE Il l! rIZs11 11] i]! J ~1111[[I ][llliiI,111 ]l11111[11]]1 Ill ble[ l.l ~l Ie~l I+m AW — 444 lllllll-lll llllllll Illllllllll I IIllllH l ill ~~~~~~~~~~~~~~~~~, II 1- I1S1 I I Iq'-11!! I44a1 l~iL~ llll 111111111111111111111111111! I 1 I~ I - 11 Il 2 11 "L""LL'-H-tIII-I-iIIIXUl n u!:m 11 111 I111 iIII/ Illll 111 11111~ Iq J~ lllllllllllllillll l~ S l lll "'tlN1' 1111.......'........

SOUND TRANSMISSION CURVE STRUCTURE 13 10I I 20 30 = 40 -_~50 60 70 [ IIrEQI r II [L v 6 7 8. 2. 4 5.6 7. 9 ZF- I 4 I i 7 8iilI 9 _ 7 t.tl if T IV:111 _ it Ii it IIII r I IIIl I M I I UH II I: ImI _ _g + 1000 1000 I 10000 I X g | g FQN I L I I IS su i X t - I I l! 10 W 11l 1; 1 1 X WSX: SI 20 ~ ~ 000"D~l0280I/t ~~L/2~ Honsycosb,1 ki., o TreatInt WIe iht 0 I971 Average Attermuation, 2890-8800 ops -. 638, ALvera~ge Attemaaation, 1830-5400 eps = 5;9.3 M-erit Facrtor - 10.9 ~ - -3- Q Factor II 11.110 3m 4~~0 FIGURE 1 5] WADC TH 58-110 23 E 91S i t~~~t E I AT4T 1 rm rx lH 1 1 1 1 ~~~~~1 1 i -71 I I T slw I IIII i I1!lT Lll ll I II.III!T,' r rr[rT~r lll~i u o u X X X t44I~itllt~le I1a H F 11 ~~~~~~~~~~ 6it 1111 Il Ml]Ll11!t li lLl:~~LLLlIIILIIIIII1 1 1111 liiiilllF~I@I~tlt tIt I I mII II!IIIIII!IIII i I!IIIII11i111111IIIIII 1i1l, 1lIiISr11 I. 1 II I I I I I I I I II I I 1 U |IIIIII1 111!1 11'IIIiII I I 1 11i IIIIL ttT T 50Sfl + TSIHr;liIII1 IHmilllII1 Q1TIIII1 11111|r!Fllilll mTj~ mmINrT r I r 1 1 I r lil Tr1TIrarlilrlll rllllIIIIr l~arT rtrl lrta~~~~nlla [ t t t W kml ill~~~~~~~~iK~~tl W4101> X mtt 11 F41011tIHU fll W g t t t$TT~itA tI~t II I 11 11180111111111111111l1|1 11 1 11 1 1 1 1 0111111 1 1 1 11 1 11t1 1 l Illllllllll ll n n. I,,, 17TT II:E IIII I I I I I I I I I * I I Ii TT15 I I I | I I I I I I I I! | I III IIlll; if HHggIIIIIIII I I I Hit11 1 1111111111111111111111111111 100~~~~~~~~~~~~~~~~~~~~~~L 100011 1000 L~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ll 1111111 I.2"ka.80l~t 90 I'1 I!111 |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 |tmit Ill" Hoeco O.)6 1i n3 I 1 t~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1~~~~~~~~0 100 10'll Awra~~e 0020" Dural 0 280-800 1b fp' 2. | 1>ll ~~~~~~~~~~~~~~~~Average Attemation,, 1830-5400O cps 59.3 y tSJI ~~~~~~~~~~~~~~Mrit Paotor -10.9,l u _1 Q ^co 11.0 f

SOUND TRANSMISSION CURVE STRUCTURE 14 10 20 T 1 I I fI i:Li 14 20 I I' I~~~~4 30 t 440 P. t;I i 1.1 I L 50 _60 <C 0 m 1T 1 m #-t i l i l i i l -"~t~i l M l ~-i;t t ttl4*lI ct l-ii-' m 1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I11 7O~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 70 I 1 f i ll I ililliHI W.,tS liiliiliiliiliill 90 1, I. 1 1111111111 II IIII;005 o 7 a 9 a 4 5 6 7 s 9 z a 4 s 6 7 a 9 1 1 r000 10000 ruXFgk1:IIFREOUENCY N CPSI I Hi=11 9.020" Dural H.2800 lb/ft2 1" Honeycomb, O.O16" skin1.8 ~ Trim O.O419 A, Treatment Weig~ht 1.2219 F m FF g L i I i~itilllllilllllLIILLIII 1111111111 w I I 1 illllIILIHIIIIIII I illlllll I/ ~~~Average Attenuation, 2890-8800 cps -I 64.6 fLIS ~~Average Attenuation, 1830-5;4OO cps = 60.5; Merit Factor = 8.02 t00;= Lm;:m;= m = _ h' ^':''' ~~~~~~~~~~~~~~~~~~~~~~I LLL-,,,,,,, iflli; 111 5 67 92 4Q Factor 6 8.35 9 100 1000 10000 FREQUENCY IN CPS L f~~~ll a * ~0020 n Dural 0. )2800 lb/ft FIGURE 16 |WADe TR 58-110 4skin 1180 I I rt IL b~~~Tri 0.0419 Al^'1 Treatment Weight 1.2219 I | Xt 11 ~Average Attemuation, 28i0-8800 cps a 64.6 gJI ~~Average Attenuation,, 1830-5400 Cps a 60.5 P 1 ~~~~Merit Factor = 8.02,3t~ _j^ " Q Factor - 8. 3 5 r

SOUND TRANSMISSION CURVE STRUCTURE 15 If~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ot~ iit:t.gx i 4t rrr 1I~1 1 I 1t rT~~...!1''!I [' I't I1~ "i 10 I~~~~~~~~~~~~~~~~~~~~~~~~I 20_ W ~ ~ ~ ~!il 1X ZJ- I: h-HI- W1g -WWk-f — 111.~1 t i 20 E S ~r t S X11: -1 —" - 1 i tt- M~l-t1-Wt!lT ~o 50 11 W41 I 1 I 1 3O tl.T'.i T W 1 lit$i ii mo~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 c~4O 5O 60 m:14 lmEW4W - I::6o - tF T 4I-i 7o0 80 ~0 5 O 7 9 2 3 4 5 0 8 9z 3 4 5 o 7 5 20 i I110 i r r0-$17 tit-ilil t[ t -t UIj t, I o00 1000 10000 FREQUENCY IN CPS __ ~1 ~~ 0,020.1 Dural 0.2800 lb/ft2 1 IISH I ~ W -t ii )~ ~ ~3/8" Honeycomb, 0.020 skin 0.955 Trim 0.O419 Treatment Weight 0.9969 3 o li! - Q Factor a 12.8 1S,.i I L 4 iF t i it'il 100 1000 F I G 1RE00 WECY TR C.P -*~~~~~~~~~~~~~~~~~~~~~~~~~~~ im.01;3n J Fotr! 2. F~iGUR i 7 WADC R9-1 0 2

SOUND TRANSMISSION CURVE STRUCTURE 16 i' 40 -— ~ —.50 ~~~~~~~~~~~~~~~~~~~7I —,.. —..i, ~. —.-4; — -..4 _60 90 S 100- 1000 10000 20" Dural 0.2800 lb/ft2 Uj ~1 1/21 Honeycomb, 0.020" skin 0.968!6 I.'~~~~~~~~~~~Merit Factor =-~ 11.2;..t- 3" 63ti1 74~ 8 9 2tQ Factor = 11.45 FIGURE 18 WADC T 8-110 26' yZ 5gIW.; lj< i I| L Attenuation, 1 0.2800 cps=60 30 Merit = 11.2;31t _ Q Factor 11.5~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ FIUR 18 i WADC~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ TR 58102

SOUND TRANSMISSION CURVE STRUCTURE 17 10! i' 20 30 IL A 3 5 i i 1 1I 40 50 _ 11III l I I I I I I!r11:i 11- 11 ~l 7nIF11 [ll L LL 11' I I I I. 1 I;' H i-C;ll ] ] 1 I I! I! I! I t I, [ 60 70 IU II I I II l, P l I I I I I I 1I 80 t~F $ 7 8 9 n 3 4 5 6 7 8 9 2 3 4 j 6 7 8 9 100 1000 10000 FREQUENCY IN CPS ___ 0.020" Dural 0.2800 lb/ft2 IIHI 1" Honeycomb, 0.020" skin 1.268 Trim 0.0L1r9 L/ I Treatment Weight 1.3099 Average Attenuation, 2890-8800 cps - 63.9 Average Attenuation, 1830-5400 cps * 59.5 Merit Factor = 6.57 1~- 3" -+QB Factor - 6.64 FIGURE 19 WADC TR 58-110 27

SOUND TRANSMISSION CURVE STRUCTURE 18 04 10 70 1 10 100: 0 50t I..E WMS -, 1, i~llllll~l tM 60 _______ 0.020 Dural7 0.2800 lb/ft2 I7 I I _ 90 7.7"::Sirm 0 h19t Averg3 4 5 6 7 8 9 2 3 4 5 p 7 8 9 100 1000 110000 FREQUENCY IG N CP WD TR 8Tri0 O2O419 A11 Treatmnent Weight 1.1539 I~~~;I 9Average Attenuation, 1830-5400 ps = 63.6.__ 3 " — ~ Q Factor = l1. 9 ~~~~~~~~~~~~~~~WADC T'Ra~~~~~~~~~~ 58-:LZO1~ 28 I

SOUND TRANSMISSION CURVE STRUCTURE 19 3O o 00.... 260 i --- C<T60 70 [[r! s1001111mt 1011 I1 70 E E I I I I I. I I Lll~lill lililil 2 0.2800 lb/ft2' it 90 4. on {n lTTI 11 I f I I IlL~l~lilILIII II —t II I 1 1 Treatment Wei 1.181I IL FIGURE 21 WADC1ratnt Weight 1.1819 58- 29 | 1,11 Average Attemationo 2890-8800 cps 64.7 Average Attenuation, 1830-5400 Cps' 60.9 s- 3,, II eMerit Factor 8.38 WADC TR 58-110 29

SOUND TRANSMISSION CURVE STRUCTURE 20 10 20 30 l+' 4 z 100 1000 110000 4i" 0~ I1[[~-!_______ 0.020" ~ ~ ~ ~'TT Ira 0280 l I0 limitit-~Tim 0.0t19 PI I I 11TI. i1 11111 11- 1 lS il1l 30H I I I I r:I II_ l1WW~~~ I X X t I ~]AIIIX2~t 1 11!1 il Ilill l FREQUENCY IN CPS L,0 b/ft2 I I I'L I II Treatment Weight 1.4319 | |2t.| Average Attenuation, 2890-8800 cps - 64. Average Attenuation, 1830-5400 cps - 59.3 L0 FF 1r it I MMierit Facfor - 6 01; 3"1 Q Factor " 5.45 FIGURE 22 WADC TR 58-110 30

SOUND TRANSMISSION CURVE STRUCTURE 21 10 30 20m.ITl iI'1Tl o~~~~~~~~I 40 40 ILL 1 I [~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~17' I W ll Illll 80 III I H 100~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I 100 00 ~~~~~~~~~~~~~~~FRQENC IN P 9~~~~~~0 0 20l Dur a 0.80 /-r, TI' _ Trim ~ ~ ~ ~~~0.02419 wlft. ~~~~~~~~~~~~~~~Treatment Weight 1.1369 Average Attemaation, 2890-8800 cps - 62.5 Average Attenuation, 1830-5400 cps=- 58.0 II~~11eit1atr 72 Qei Factor = 7.21

SOUND TRANSMISSION CURVE STRUCTURE 22 10 20 30 50 I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-,, 7O~~~~~~~~JZ 40 TT _ I I k S t < 1 Wffl;;; 40 ~~~~~~~~~~~~~-'0 00 + 5 B 7 8 9 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 lOO lQOO 10000 7-t H~FREQU CY IN CPS.It 0.0"(t Dural. Oe~2800 lb/ft2 F rl1" Honeycomb, O.022 Mskin 1.188 | |;''|- ~Trim O0.0419 rn ll Treatmenet Weigh 1.2299 ~wkll ~Average Attenuation, 2890-8800 cps = 66.0 80 IAv a Av ttenuation, 1830-5400 cps 60.1 t * ~~~~Merit Factor = 7.42 0- 3 " I i i -f' 40 1 Ili-~~~~L~li!( i i ii Illili I I: I I II I~~~~~~~~i Il~~i I Hil I:li 90"~ Factor 4I i I6.2 FIGURE 24 WADC TR 58-110 32I. 50 +r'i:1100100 100 60 I I I~~FRQUNY N P 0.21 ua.80l/t 111 Honeycomb, 0.02C)"skin 1.1881~~~~-t!llil i~llll IiI i1 1111 ~ 11 IiIlllllllTrim 0llllll III 0419 lllll l 70~~~~~~~~~Te —et egt129 AveageAttnutio, 290-80 cp n 6. Averge tteuaton,1830.140 cs =60. ~ttt~t i~~ttt~it/- Merit Factor - 7.42IIi tt~tt III

SOUND TRANSMISSION CURVE STRUCTURE 23 0 0 i'' I 107 20 30 4 LI 640 1 T1 00 55W0rtm0! 1 60 10 0 00 80 11 f i FREQUENCY IN CPS L il0.020" Dural 0.2800 lb/ft2 Old I 1" Honeycomb, 0.25" skin 1.305 Trim O.0419 1 5~ 11Treatment Weight 1.3469 Average Attenuation, 2890-8800 cps = 66.1 Average Attenuation, 1830-5400 cps = 59.8 Merit Factor s 7.87 3"- Q Factor - 6.46 FIGURE 25 WADC TR 58-110 33

SOUND TRANSMISSION CURVE STRUCTURE 24 10 30 X ~ 50 $, S W W W i t~~~~~~~, 4 100Y7 56789 2 3 456789 2 3 4 56789 100 1000 10000 FREQUENCYINCOPS 2 O_.020" Dural 0.2800 lb/ft2 1/2" Honeycomb, me tal 1.19.50 Treatment Weight 1.2369 Average Attenuation, 2890-8800 ops - 66.6 Average Attenuation, 1830-5hO0 cps = 62.9;.Merit Factor = 9.46 ~-3" - Q Factor - 10.0O FIGURE 26 WADC TR 58-11o 54 1'-'LI[II [il [ -1 11 11 II l ~r2; -tt-r-rii -' rr t~r<1I I1 <F! 1 1 lm~r~r s n-zI<rS-ST1 l i 1l I-L7 7n;;1'111!1! ~ I'I! II|t I r —llTri -lll' +l,11! IrI T1l rrr -~AT ll l i L ( |[ 0 -IDIfil 4II|i"|g;1;.I 1_ tlI|tII1_4ztiAT i1 H H | W — a~i-Xl 1111X11ll1 1! I Illllt i fi E E -Tit'll | 11 -11t1111114 —I!; I 9 ~lIIITI 4FI I|IiIIIIIIiII 1 IIIll1 II*I|I1lIl4X l 11 } i,,, L }!'l|!2||t||$'11V T 2} 5 I 1 71 -7 {6 i|i4 I I!',I. III; 1 i I I 1V I L III IIj, I I. II, II T 11 m 1 r I I I I I IIi 11 Ir4l II 1a'1 ilr~ T7 L1 n 11 11 i1,1111 11 iI r I rTI IIT]I i11ll rt -lI 4-ImE 5 6 7 + 100 ~~~~~~~~~~~~~~~~~~~~~V1000 000 | |5 ||_ Trim 0.0419~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~14 1 I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I'SI | 4 55erit Factor = i.46~~~~~~~~~~~~~~~~4: WAD TR HIM13

UNIVERSITY OF MICHIGAN 3 9015 03466 6027