Eight times you will hear a reference noise band followed by a test band of increasing width and identical power. Compare the loudness of reference and test bands
Critical bands by loudness comparison
This demonstration provides another method for estimating critical bandwidth. The bandwidth of a noise burst is increased while its amplitude is decreased to keep the power constant. When the bandwidth is greater than a critical band, the subjective loudness increases above that of a reference noise burst, because the stimulus now extends over more than one critical band.
The subjective loudness of a complex tone is fairly complicated, but for combining the loudness of two or more tones, the following rules of thumb usually apply:
Demonstration 3. Critical Bands by Loudness Comparison (1:09)
1. If the frequencies of the tones lie within the critical bandwidth, the loudness
is calculated from the total intensity: I = I1 + I2 + I3 + .....
2. If the bandwidth exceeds the critical bandwidth, the resulting loudness is greater than obtained from a simple summation of intensities. As the bandwidth increases, the loudness approaches (but remains less than) a value that is the sum of the individualloudnesses: 8 = 81 + 82 + 83 + .....
Demonstration 3. Critical Bands by Loudness Comparison (1:09)
In this demonstration, a noise band of 1000-Hz center frequency and 15% bandwidth (930-1075 Hz) is followed by a test band with the same center frequency and bandwidth (see 1 in the figure below). The bandwidth of the test band is then increased in 7 steps of 15% each, while the amplitude is decreased to keep the power constant. When the bandwidth exceeds the critical bandwidth, the loudness begins to increase.