Two main reasons for using dual-tone multi-frequency for touch-tone dialing are:
Dual-tone multi-frequency dialing refers to the fact that when a non-rotary phone dials, it sends two tones at the same time. When these tones are put together, a distinct sound is created, which is recognized by the switch at your phone service provider.
Touch Tone was a trademarked name used for the system technically known as DTMF, or Dual-Tone Multi-Frequency, dialing. In DTMF, pressing each key on a telephone dial produces two different tones. Each row and each column of the dial is assigned a specific frequency (pitch) of tone, so the combination of the two tones uniquely identifies the key that was pressed. The telephone switch receives and decodes the tones in order to process the call. This is in contrast to pulse or rotary dialing, in which a series of electrical pulses or clicks are sent through the telephone wire, either by turning a rotary dial or by generating the clicks electronically. The telephone switch counts the number of clicks to get each digit that is dialed.
1) Pulse dialing sends number in terms of pulses while the tonedialingsends the number in form of tones " dtmf"2) pulsedialingis slower than tone dialing 3)pulse dialing doesn't use keypad while tone dialing use 4) pulse dialing isobsessed while tone dialing is modern
NOT QUITE AN ANSWER I don't know why, from a historical perspective. Possibly because it's the simplest way to arrange the keys using the tone dialing scheme. The individual keys' dialing tones are created by mixing two tones. There are three tones for the columns, and four for the rows. Each key makes a predefined combination tone.
No, the ear cannot distinguish two pure tones having the same frequency and amplitude.
Frequency Theory
A pulse dialing phone is a telephone that can dial a number using a series of clicks (pulses) instead of tones. All rotary telephones use pulse dialing; many pushbutton phones, especially older models, have a switch for tone or pulse.
The tone of a sound wave is determined by its frequency. Higher frequencies produce higher tones, while lower frequencies produce lower tones.
The DTMF (Dual-Tone Multi-Frequency) setting on a cell phone typically refers to the length of the tones produced when dialing a number. The choice between long, short, or off depends on personal preference and the specific requirements of the user. Long tones may be preferable for individuals who need auditory feedback, while short tones can help expedite the dialing process. Turning the DTMF off can be useful in environments where noise interference may disrupt the tone recognition.
DTMF means Dual Tone Multi Frequency this is every key on your phone key pad, each key generates two tones over top of each other hence the Dual Tone of DTMF. This also applied to touch tone telephones that are hardwired in homes and businesses, they also use DTMF keying.
because their ears are more developed.
I think that humans can hear low frequencies the best because they travel farther and the wave form is wider. High frequencies break up easily against walls and buildings. Think about a loud car stereo on your street.