Fletcher-Munson Curves Essay example

791 WordsFeb 6, 20124 Pages
The ears are one of the most complex and interesting systems thats human body has and the sounds we hear are actually in many different parts deflected, absorbed, and also filtered by our different body parts. It's then collected by our pinnae (the external part of or ears), whose dimensions further affect the sound on its way into ear. There, vibrations are translated into signals, which are interpreted by your brain. In the 1930s, two scientists at Bell Labs, Harvey Fletcher and Wilden A. Munson researched this process and what they discovered has changed and affected how we as humans understand the hearing process. Harvey Fletcher and Wilden Munson revealed, among other things, that the human ear is not linear, and is not capable of…show more content…
The Loudness button on consumer stereo receivers is an equalization circuit that boosts the highs and lows as the volume is lowered so the music will sound the same whether soft or loud. Noise-shaping circuits filter dither and quantization noise into the extreme upper range, where we will simply notice it less. To describe the concept of equal loudness regardless of frequency, the unit phon was developed. Each curve of the equal loudness contours defines a single phon level. For example, the curve that is 40 dB SPL at 1 kHz is defined as 40 phons; 40 phons at 10 kHz is therefore approximately 50 dB SPL and at 100 Hz slightly more than 60 dB SPL. Phons and decibels SPL are the same for a 1 kHz tone — an increase of 10 phons is equal to an increase of 10 dB at 1 kHz, but it may be more or less at other frequencies. Many audio measurements are made using weighting curves that attempt to skew the results in favor of the way we actually hear. For example, the signal-to-noise ratio of a microphone preamp might be listed as 108 dB A-weighted, or sometimes just 108 dB(A). This means that the noise was filtered before measurement to exclude the extreme lows and highs to approximately the same degree our ears do at 40 phons. The rationale is that if we listen to the device at that level, then we will perceive the noise floor to be
Open Document