ECE 445S Real-Time DSP Lab - Lecture 3 - Announcements

How a generated sound is heard -- it's complicated

There are at least three factors to how a sound is heard from an audio perception view:
  1. Playback system. Playback systems on laptops and tablets attenuate frequencies below 200 Hz and above 15 kHz. Frequency response plot.
  2. Listening environment. Could be noisy. Tones and other signals might also be playing. There are reflections off of walls, floors and ceilings. All this can be mitigated to some extent by listening over earbuds or headphones.
  3. Human auditory system. A human auditory system typically has a stronger response to mid-range frequencies than low or higher frequencies; e.g., the response to 880 Hz is generally higher than the response to 440 Hz. This assumes that the human auditory system has not suffered any damage or infection to reduce its sensing capabilities. Here are several models of frequency responses for human hearing. Here measurements of frequency responses for human hearing from 500 Hz to 6000 Hz due to age.

How significant is an increase of 10 dB in sound level?

It will sound twice as loud to the human auditory system: 

Understanding Sound Intensity: How Many Decibels Does It Take To Double Volume?
Likewise, a decrease of 10 dB in the sound level is perceived by the human auditory system as half as loud.

When listening to sound, there are additional factors such as audio cognition, interplay with what a human might be seeing, one's emotional state, and ability to focus on the sound.

Last updated 09/09/26. Send comments to Prof. Evans at bevans@ece.utexas.edu