TY - JOUR
T1 - The Selection of Modulation Rates for Frequency Modulated Sound Field Stimuli
AU - Walker, G.
AU - Dillon, H.
PY - 1983
Y1 - 1983
N2 - The selection of modulation rales for frequency modulated sound field stimuli. Walker, G. and Dillon, H. (Nationa Acoustic Laboratories, Sydney, Australia). Scand Audiol 1983, 12 (151-156). Frequency modulated (FM) tones are used in sound field audiometry in order to avoid problems caused by standing waves. The FM stimuli to be used must be specified in terms of bandwidth (twice the frequency deviation), modulation rate and modulation waveform. This paper deals with selection of the modulation rate. Improved field uniformity obtained with FM tones relies upon the ear averaging the sound intensity as the frequency sweeps. The modulation rate must be less than about 1/3 of the frequency deviation in order to provide sufficient spectral components to ensure reasonable averaging across the frequency band. If the rate is too low threshold will be determined by the peak intensity during the sweep. For normal listeners a modulation rate of 5 Hz is just satisfactory but in the hearing impaired a higher rate is required because of their altered temporal integration characteristics. A suitable value for the modulation rate can be inferred from the literature on temporal integration and the acoustic characteristics of typical test rooms. The optimum rate increases with the stimulus centre frequency, but a constant rate of 20 Hz appears to be acceptable.
AB - The selection of modulation rales for frequency modulated sound field stimuli. Walker, G. and Dillon, H. (Nationa Acoustic Laboratories, Sydney, Australia). Scand Audiol 1983, 12 (151-156). Frequency modulated (FM) tones are used in sound field audiometry in order to avoid problems caused by standing waves. The FM stimuli to be used must be specified in terms of bandwidth (twice the frequency deviation), modulation rate and modulation waveform. This paper deals with selection of the modulation rate. Improved field uniformity obtained with FM tones relies upon the ear averaging the sound intensity as the frequency sweeps. The modulation rate must be less than about 1/3 of the frequency deviation in order to provide sufficient spectral components to ensure reasonable averaging across the frequency band. If the rate is too low threshold will be determined by the peak intensity during the sweep. For normal listeners a modulation rate of 5 Hz is just satisfactory but in the hearing impaired a higher rate is required because of their altered temporal integration characteristics. A suitable value for the modulation rate can be inferred from the literature on temporal integration and the acoustic characteristics of typical test rooms. The optimum rate increases with the stimulus centre frequency, but a constant rate of 20 Hz appears to be acceptable.
UR - http://www.scopus.com/inward/record.url?scp=0020515738&partnerID=8YFLogxK
U2 - 10.3109/01050398309076240
DO - 10.3109/01050398309076240
M3 - Article
C2 - 6648312
AN - SCOPUS:0020515738
SN - 0105-0397
VL - 12
SP - 151
EP - 156
JO - Scandinavian Audiology
JF - Scandinavian Audiology
IS - 3
ER -