stimulus error
5.57 stimulus error. Error introduced when nonsensory events or irrelevant stimuli influence a subject’s response to a stimulus. Annotation Examples of nonsensory events and irrelevant stimuli are introspection and ambient sounds, respectively.
signal-to-noise ratio level
5.56 signal-to-noise ratio level. Ten times the logarithm to the base ten of signal-to-noise ratio. Symbol, NSN. Unit, decibel (dB). Annotation 1 When measures proportional to signal power, S, and noise power, N, can be determined separately and independently, signal-to-noise ratio level is given by: NSN = 10 lg(S/N) dB. Annotation 2 When measures proportional to signal and noise power cannot be determined separately and independently, the level of the ratio of signal-plus-noise to noise, N’SN is given by: N’SN = 10 lg[(S+N)/N] dB.
signal-to-noise ratio
5.55 signal-to-noise ratio. Ratio of a measure of a signal to the same measure of the noise. The measure may be electric power, time-mean-square voltage, time-mean-square current, or the acoustical analogs, acoustic power, time-mean-square sound pressure, time-mean-square sound particle velocity, respectively. The frequency range and statistical properties of the signal and the noise should be stated explicitly. Abbreviation, SNR or S/N. Annotation In controlled situations it may be possible to determine the measures of the signal power and the noise power separately and independently. In most natural conditions, however, measurements are limited to determining signal-plus-noise and noise-alone. Signal-to-noise ratio then becomes a derived quantity.
signal processing
5.54 signal processing. Techniques or algorithms for the generation, transformation, conversion, manipulation, or analysis of analog or digital data in the time or frequency domain, typically used for the reduction or extraction of information. Examples include, but are not limited to: Filtering, spectral analysis, dynamic range compression or expansion, noise reduction, and calculation of measures such as loudness, audibility, or estimates of intelligibility, etc.
Weber ratio
5.53 relative differential threshold; Weber fraction; Weber ratio. Ratio of the differential threshold to the absolute magnitude of the stimulus to which it is related. Annotation 1 The differential threshold and the absolute magnitude of the stimulus must be stated in the units of the stimulus, which may be pressure, intensity, frequency, etc. Annotation 2 The Weber ratio is constant in the middle range of stimulus values.