MIL Standard Earphones Acoustics Testing

Project Description

I am looking for a Contract Laboratory for Acoustic testing performed on a QTY 5 Earphones H-87B/U type 2 Earphone per MIL-DTL-18239 REV. E for frequency response per Paragraph 3.4 ,3.4.1, 3.4.1.1 & 4.6.1 & Test Circuit Figure 4 & 6cc Coupler Figure 5 (see attachments)

3.4 Performance.

3.4.1 One thousand (1,000) Hz sound pressure output. The normal sea level sound pressure versus
frequency characteristics of the earphone shall be 103 ± 2 dB above a reference level of relative to 20 µPa
(micro-Pascal) (0.0002 dyne/cm2) with 1 milliwatt rms power at 1,000 Hz applied to the earphone
terminals, when tested in accordance with 4.6.1.

3.4.1.1 Sound pressure output versus frequency. The normal sea level sound pressure versus
frequency characteristics of each earphone shall not deviate from the 1,000 Hz response by more than the
values shown in table I, when tested in accordance with 4.6.1.
TABLE I. Deviations of sound pressure versus frequency.

Frequency in Hz Deviations (in dB)
Minimum Maximum
100 to 2,500 -3 +3
2,501 to 3,000 -3 +3
3,001 to 7,000 -7 +6
=