I. Audibility function - threshold vs. frequency
A. Humans hear between 20-20,000 Hz
B. Most sensitive around 3,000 Hz
II. Pitch = "the aspect of hearing that allows sounds to be ordered from high to low."
A. High frequency = high pitch, low frequency = low pitch
B. Fundamental frequency - contains the most energy
C. Intensity influences pitch
D. Other frequencies influence pitch
E. Missing fundamental phenomenon
III. Physiology: 2 theories
A. Place theory
1. Traveling wave; snapshots of the wave
2. Location of the peak of the wave indicates frequency
3. Tonotopic organization - orderly arrangement of frequency representation [Figure]
4. Problem - No peak for very low frequencies
B. Frequency theory
1. Frequency coded in firing rate of the hair cells
2. Problem - cells can't fire fast enough for very high frequencies
C. Resolution - Place theory operates for high frequencies, Frequency theory operates for low frequencies
IV. Auditory nerve and the frequency tuning curve
B. Steeper at high frequency end
C. Have to look at the pattern of responses across many auditory nerve cells
V. Critical Bands
A. Masking - the presence of one sound increases the threshold for detecting another sound
B. Noise
C. Bandpass noise - center frequency and bandwidth
D. Critical band - band of frequencies that will mask a tone
