Multilevel Pistonphone for Producing Low-Frequency Sinusoidal Pressure Fields.
Abstract
This pistonphone is a mechanical device that can generate high-level, low-frequency, sinusoidal pressure fields in small closed volumes over a wide dynamic range for purposes of microphone calibration and laboratory tests. This report describes the device, its performance characteristics, and operational/maintenance procedures. The pistonphone uses two interchangeable pistons (0.39 and 2.05 cm. diameter) and four interchangeable cylindrical chambers (17, 99, 310, 1105 cc.) to produce sound pressures at 8 discrete levels ranging from 109 to 174 dB (re. .00002 newton/sq) over a frequency range of 0.5 to 90 Hz. Tables and graphs present those factors required to compensate for atmospheric pressure changes, isothermal losses, wavelength effects, nonsinusoidal piston motion, nonlinear compressibility of the gas media, vibration, and microphone equivalent volume. This system provides the capability to measure microphone linearity, frequency response and absolute sensitivity to within + or - 0.2 dB at all levels except 174 dB (+ or - 0.35 dB) for acoustic pressure fields within the limits indicated. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1976
- Accession Number
- ADA026023
Entities
People
- Carl G. Toler
Organizations
- Air Force Research Laboratory