NBSIR 76-1179

Attack and Release

Characteristics of Compression

Hearing Aids

Edwin D. Burnett and Martin A. Bassin

Institute for Basic Standards

National Bureau of Standards

Washington, D. C. 20234

December 1976

Final

Prepared for Department of Medicine and Surgery

Veterans Administration

Washington, D. C. 20422

NBSIR 76-1179

ATTACK AND RELEASE

CHARACTERISTICS OF COMPRESSION

HEARING AIDS

Edwin D. Burnett and Martin A. Bassin

Institute for Basic Standards

National Bureau of Standards

Washngton, D. C. 20234

December 1976

Final

Prepared for Department of Medicine and Surgery

Veterans Administration

Washington, D. C. 20422

X*1 °'

V'Xv’ •'•e.u o'

U S DEPARTMENT OF COMMERCE. Elliot L. Richardson. Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

ATTACK AND RELEASE CHARACTERISTICS OF COMPRESSION HEARING AIDS

Edwin D. Burnett and Martin A. Bassin

Institute for Basic Standards

National Bureau of Standards

Washington, D.C. 20234

ABSTRACT

The attack and release time characteristics of 81 compression

hearing aids are presented. The input signal used was that specified in

the standard, ANSI S3. 22.

iii

INTRODUCTION

The attack and release time characteristics of compression hearing

aids were recorded by NBS and incorporated for the first time as part of

the regular testing of FY-76 hearing aids for the Veterans Administration.

This report describes the method used to obtain the results and presents

oscilloscope recordings of the envelopes of the attack and release intervals.

The actual attack and release times can be obtained from these recordings

using the definitions given in Figure 1.

METHOD

To determine the attack and release times of hearing aids tested by

NBS the envelope input signal shown in the top of Figure 1 is used. This

is the signal specified in the standard, ANSI S3. 22 (1). The carrier

frequency of this signal is 2 kHz. The amplitude of the input signal corresponds to a sound pressure level (SPL) of either 55 or 80 dB re 20 yPa.

To determine the attack time of the hearing aid the SPL is increased abruptly

from a SPL of 55 dB to one of 80 dB. The release time is determined by

abruptly reducing the SPL from 80 dB to 55 dB. An idealized envelope of the

output signal from the hearing aid is shown in the bottom of Figure 1. Although one burst of the 2 kHz signal shown in the top of Figure 1 would be

sufficient for the measurement, in practice it is convenient to have this

signal repeat itself a sufficient number of times so that adjustments to

signal level into the oscilloscope can be made prior to taking the permanent

recording of the output signal. The duration of the signal at each of the

two SPLs is not critical; however, it must be somewhat longer than the time

required for the hearing aid output to reach steady-state conditions after

1
the level is changed. A duration of 200 ms for each of the signal levels

has been found sufficient for most hearing aids.

•

I

1 To minimize the occurrence of spurious transients in the input signal

envelope, the abrupt changes in the levels are made at a time corresponding

to a zero voltage crossing of the input carrier signal.

The test is performed in a free field. The hearing aid volume control

is turned to its maximum setting and its receiver is coupled to a Zwislocki

coupler having a type HA-2 adaptor. This adaptor is used even for high-pass

hearing aids which are normally tested for their other characteristics on an

open coupler.

The coupler's microphone output voltage is displayed on a large-screen

(15 x 20 cm) oscilloscope. A total sweep time of 0.5 seconds is used so

that the entire duration of the high and low amplitude portions of the signal

are displayed. The vertical amplitude control on the oscilloscope is

adjusted so the initial overshoot during the attack portion of the signal

goes beyond maximum limits of the screen. This permits one to obtain a

recording with higher amplitude resolution for those portions of the signal

that are used to determine the attack and release times. A second oscilloscope recording is made usually with a total sweep time of 0.05 seconds,

with the amplitude attenuated such that the entire overshoot region can be seen.

On each of the figures depicting the envelope of the output signal of

the hearing aid are three labels. The first label indicates the alphanumeric

code corresponding to hearing aid manufacturer and model number which are

given in Table 1. The second label denotes the total duration in seconds

2
of the sweep of the horizontal 'axis. This axis is linear so that half the

length of the axis corresponds to half the total duration, and so on. The

third label indicates the amount of attenuation of the signal relative to

that used to obtain the preceding record of the attack and release portions

of the same hearing aid. For some of the hearing aids a number is shown

above the high-level portion of the signal. This number is the steadystate output SPL at 2 kHz for an input SPL of 80 dB.

Figures 2 and 3 show the output of the "1/2 inch" reference microphone.

The minor irregularities in the steady-state portion of the signal are

caused by low frequency acoustic noise. These components do not affect the

test results since they fall below the frequency region passed by the hearing

aids. Figure 3 shows that a time interval of 3 msec (6 cycles of the 2-kHz

signal) is required for the acoustical signal to reach steady-state

conditions. The peak value of the first cycle of the high amplitude portion

of the signal is approximately 1.75 dB below the steady-state peak value.

REFERENCE

1. ANSI S3. 22 (1976), "Specification of Hearing Aid Characteristics,"

American National Standards Institute, New York, N.Y.

3
TABLE I

Hearing Aid Codes, Manufacturers, and Models

Code Manufacturer Model

AT310-AT312 Audio tone A24 Compression

DA217-DA219 Dahlberg HT1233 Compression

DX145-DX147 Danavox 745 AGC

DX148-DX150 Danavox 745 DAGC

DY001-DY003 Dynatone 500 P

FI229-FI2 31 Fidelity F34

FI232-FI234 Fidelity F52Bicros

FI238-FI240 Fidelity F58D

HC019-HC021 HC Electronics HC527LW

HC022-HC024 HC Electronics HC527SEW

HC025-HC027 HC Electronics HC801AGC

LE127-LE129 Lehr Star 6DRC

N0166-N0168 Norelco HP8234AGC

N0172-N0174 Norelco HP8274 Lim, Time, ' OI214-OI216 Oticon E14C

QU259-QU261 Qualitone CNE

RA256-RA258 Radioear 1063

SI157-SI159 Siemens 24PP-AGC-I

ST004-ST007 Starkey 4112

TE301-TE303 Telex 336DC

UN001-UN003 Unitron 295T

UN007-UN009 Unitron 695H

UN013-UN015 Viennatone 88AMA-D

UN019-UN021 Viennatone 90/AOC-PC

WI109-WI111 Widex AIT

WI121-WI123 Widex A6T

ZE307-ZE310 Zenith Command 100D

4
80 dB THE INDICATED AMPLITUDE

CORRESPONDS TO THE

rms SPL

ENVELOPE OF INPUT SIGNAL

ENVELOPE OF OUTPUT SIGNAL

Fig. 1. Idealized envelopes of hearing

aid input and output signals.

5

2

dB
Fig 2 Voltage output from the

reference microphone.

6
0.05 sec sweep

WW+HX-. .-;U4 v •* ..«l|i .* •.. •• • ‘1 ... I.

Fig. 3 Voltage output from the

reference microphone viewed

with an expanded time scale.

7
8
AT-3I0

0.05 sec sweep

0 dB
116.5

10
It

0.05 sec sweep

0 dB

11
117

AT-312

0.5 sec sweep

•-;.*** **,** V •,*** •

12
AT-312

0.05 sec sweep

0 dB

f :

13
14
BA-217

0.05 sec sweep

-2 dB
16
!

i

I

!

:

DA-218

0.05 sec sweep

-2 dB

17
18
DA-219

0.05 sec sweep

-2 dB
20
DX-145

0.05 sec sweep

-1 dB

;1

«•••* •*. - wgtfggm
I

'

22
Dx-146

0.05 sec

-4 dB

sweep
24
dx-147

0.05 sec sweep

-6 dB
DX-148

0.5 sec sweep

26
DX-148

0.05 sec sweep

-6 dB

-- 1 » •w n, in iinpupmu^w^ii m- *>•—

-
28
DX-149

0.05 sec sweep

-4 dB ,

29
30
DX-150

0.05 sec sweep

-5 dB
32
DY-001

0,05 sec sweep _H.dEL - - *• - —-

"

Al»v*
i

34
I
36
I

Dy-003

0.05 sec sweep

0 dB

j

37
I

130

' It#*. « -•• .« is >4.. * '••..• r *-.-!• * — -

• ••! '++*

38
FI-229

- 0.05 sec sweep

0 dB

i
40
I*

1 1

41
42
FI-231

0.05 sec sweep

OdB
44
45
46
47
an

48
49
50
51
» 52
FI-239

0.05 sec sweep

-10 dB
54
55
I
57
58
59
60
61
62
mmmmmaBS

63
64
65
66
1
68
HC-025

0.05 sec sweep

-3 dB
70
HC-026

0.05 sec sweep

-4 dB
72
HC-027

0.05 sec sweep
74
IE-127

0.05 sec sweep

-4 dB 8**>**• —•-

— *••• ^ « 1. -
:r..: '--^

;V: 'K' %', •: - . .-

;.

Si] ^

LE-128

0.5 sec sweep

W' II

124
LE-128

0.05 sec sweep

-4 dB

LE-129

0.05 sec sweep

-6 dB
!

80
NO- 166

0.05 sec sweep

-3 dB

—iyk.HbH s
(

82
NO-167

0.05 sec sweep

-3 dB
.

84
NO- 168

0.05 sec sweep

-3 dB
mtitm

0.5 sec sweep

86
NO- 172

0.05 sec sweep

-1 dB

m*f*di+* •***•+- —4. ^1.

87
88
NO-173 0.05 sec sweep

-3 dB

***** lawft
90
!

NO-174

0.05 sec sweep

0 dB

91
01-214

0.5 sec sweep

u. • m iihmigmj

92
t

01-214

0.05 sec sweep

-5 dB

gWMIBUlBlU
94
01-215

0.05 sec sweep

-6 dB
*»**-’*» - •. * •

. «r»- .•»••**..’• *sw >1 •,.!•• ^#*4**<a ii i a

117.5

01-216

0.5 sec sweep

96
1

97
98
QU-259

0.05 sec sweep

-15 dB

1 1 1 f ny.gtpfqg

99
QU 260

sec sweep

100
QU-260

0.05 sec sweep

-15 dB

mmMm*

101
i )

I

102
QU-261

0.05 sec sweep

-15 dB

103
RA-256

0.5 sec sweep

i

104
RA-256

0.05 sec sweep

-13 dB

•• *+-r*r.

105
106
I

107
108
RA-258

0.05 sec sweep

-13 dB

-p*» <***<•"«>* - 1 m nmtmmmt&i&fo

109
¥y**t*m*mm 4li M i i in Xgfl

110
Ill

ESS
I

112
si-158

0.05 sec sweep

V.'.
I

114
SI-159

0.05 sec sweep

115
116
An

St-004

0.05 sec sweep
118
119
*!»> ni (

I

120
121
TlS-JUl

0.5 sec sweep

***** mt**¥***t* IW' MMW mmmmm

122
TE-301

0.05 sec sweep
•rw

TE-302

0.5 sec sweep

mm

124
125
mmmt

126
127
128
UN-001

0.5 sec sweep

-5 dB

- - y J m i qn ip^WMrtfenaiiWM^

129
130
MMH

131
132
133
134
135
136

0.05 sec sweep

I

140
141
WI-109

0.05 sec sweep

-6 dB
143
!

144
145
\

146
I

mSM ms* £ mum

WI-121

0.5 sec sweep

147
sweep
149
WI-122

0.5 sec sweep

Amplitude reduced 10 dD.

nwwmwmiwuo w ww n -.i.n f
151
152
WI-123

0.05 sec sweep

. *•»> «»n— ****$»&*>* e»»~H-tm
\

zs-309

0.1 sec sweep

-8 dB

. mi i nmj mnp

ij

154
155
i

156

158
159
\

118

UN-008

0.5 sec sweep

mmmm mm

160
161
162
UN-009

0.05 sec sweep

-3 dB

'I'm 1 !

163
\

164
VN-013

0.05 sec sweep

-7 dB
\

166
VN-014

0.05 sec sweep

-8 dB

1 n ..HWPUllEBim , «

167
168

170
171
incci g 

* 1 '

4. TITLE AND SUBTITLE

Attack and Release Characteristics of Compression

Hearing Aids

5. Publication Date De center 1976

6. Performing Organization Code

200.03

7. AUTHOR(S) ^ Edwin D. Burnett and Martin A* Bassin8. Performing Organ. Report No. NBSIR 76-1179

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2003416

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Department of Medicine and Surgery

Veterans Administration

Washington, D.C. 20422

13. Type of Report & Period

Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less (actual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

The attack and release time characteristics of 81 compression hearing aids are presented. The input signal used was that specified in the standard, ANSI S3. 22.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Attack and release characteristics; compression; hearing aids

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