What Equal Loudness Curves Show

Curves illustrate:

1. insensitivity of the ear to low-frequency tones:
   • low-frequency tones must be at a higher SPL to sound equally loud as higher-frequency tones;
   • e.g. a 10-phon 50-Hz tone has to be 40 dB greater than a 2000-Hz tone to be equally loud.

2. insensitivity of the ear to very-high-frequency tones:
   • e.g. a 10-phon 10-kHz tone has to be 10 dB greater than a 1000 Hz tone to be equally loud.

3. sensitivity of the ear to 2-4 kHz tones:
   • how to you account for the dip at 2-4 kHz?
   • why another dip at around 12 kHz?

4. loudness variation with frequency is dependent on the sound level:
   • range dips more significantly in lower curve
   • curve is flatter at higher sound levels

FrequencyAndLoudness.pd