Coad_Margaret_GoForthFinalPoster
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• Six different phones were tested: two Apple smartphones (red), two Android smartphones (green), and two conventional phones (blue). • A white noise sound signal was played into each of the phones for two cases: recording and playback, and transmission. • For recording and playback, the sound was recorded and played back by the same phone. • For transmission, the sound was played into one phone in a call with another of the same phone. • The output sound was recorded by the reference microphone and then compared with the signal created by recording the white noise input with the same reference microphone. • A frequency response function, which can be thought of as a ratio of the output amplitude to the input amplitude for each frequency, was determined for each phone. • A cutoff frequency, which represents the frequency above which sound does not pass through at an appreciable level, was also defined for each phone. Playback and Transmission Frequencies of Cell Phones Margaret Coad 2.671 Measurement and Instrumentation The frequency response of six different cell phones was measured to characterize their ability to play back and transmit the human voice. White noise was recorded by each of the six phones and played back into a reference microphone. The resulting signal was used to determine the frequency response function of each phone. For four of the phones, the same procedure was carried out for a phone call between two of the same phone. For recording and playback, the iPhone 4 had the highest cutoff frequency, 15,564 ± 708 Hz, while the LG enV 1 had the lowest cutoff frequency, 3,470 ± 343 Hz. However, for transmission, all phones had similar cutoff frequencies, close to 3,600 Hz, near the network standard of 3,400 Hz for telephone transmission. Thus, for sound transmission, all phones have similar sound quality, but for recording and playback, smartphones have higher sound quality than conventional cell phones. Abstract Introduction • For recording and playing back sound, smartphones have higher cutoff frequencies, and thus better sound quality than conventional phones, most likely because they have more memory and are used to play music. • For regular phone calling, all phones are equal in quality, with a cutoff frequency of approximately 3,600 Hz, due to the frequency filtering of the network at 3,400 Hz. • On HD Voice networks, smartphones will be able to transmit sound with higher quality than conventional phones, as they are capable of recording and playing back sound with a cutoff higher than 7,000 Hz. Conclusions Dec. 3, 2013 Recording/Playback Summary Plot References Acknowledgements Thanks to Dr. Braunstein, Dr. Hughey, Prof. Leonard, and those who allowed their phones to be tested. • Humans can hear sound in the frequency range from 20 Hz to 20,000 Hz. • To save digital storage space, cell phone networks transmit sound only within a diminished frequency range, traditionally between 300 Hz and 3,400 Hz, represented by f s tel , in the diagram below. • Input sound is also filtered by the microphone and speaker of the transmitting and receiving phones, represented by f c in , f s in , f s out , and f c out . • Speech filtered to below 3,400 Hz sounds muffled and thin, and certain consonants such as “s” and “f” are indistinguishable from each other. • A higher range of transmission frequencies is desirable for intelligibility and clarity. • A technology new to the US in 2013, called HD Voice, allows certain phones on certain networks to transmit double the frequencies, expanding the range to 50 Hz to 7,000 Hz. Methods Cutoff Frequency: 11,110 ± 1202 Hz Cutoff Frequency: 15,564 ± 708 Hz Cutoff Frequency: 15,335 ± 94 Hz Cutoff Frequency: 6,775 ± 634 Hz Cutoff Frequency: 3,609 ± 166 Hz Cutoff Frequency: 3,470 ± 343 Hz Cutoff Frequency: 3,674 ± 65 Hz Cutoff Frequency: 3,766 ± 146 Hz Cutoff Frequency: 3,685 ± 278 Hz Cutoff Frequency: 3,569 ± 32 Hz Transmission Summary Plot Recording/Playback Results Transmission Results Traditional Network Cutoff: 3,400 Hz HD Voice Cutoff: 7,000 Hz 1. Malcolm J. Crocker, Handbook of Noise and Vibration Control, John Wiley & Sons (2007). 2. Alexandra Chang, “How HD Voice Works to Make Your Calls Sound Drastically Better,” (2013), http://www.wired.com/gadgetlab/2013/04/how- hd-voice-works-to-make-your-calls-clearer/ 3. Eberhard Hänsler, Gerhard Schmidt, Speech and Audio Processing in Adverse Environments, (2008), http://link.springer.com/book/ 10.1007%2F978-3-540-70602-1 Future Work • Explore other features of the frequency response function besides cutoff frequency, e.g. dips and spikes at certain frequencies, and their effect on sound quality. • Test phones capable of HD Voice to confirm larger frequency transmission range.
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Transcript of Coad_Margaret_GoForthFinalPoster
• Six different phones were tested: two Apple smartphones (red), two Android smartphones (green), and two conventional phones (blue).
• A white noise sound signal was played into each of the phones for
two cases: recording and playback, and transmission. • For recording and playback, the sound was recorded and played
back by the same phone. • For transmission, the sound was played into one phone in a call
with another of the same phone. • The output sound was recorded by the reference microphone and
then compared with the signal created by recording the white noise input with the same reference microphone.
• A frequency response function, which can be thought of as a ratio of the output amplitude to the input amplitude for each frequency, was determined for each phone.
• A cutoff frequency, which represents the frequency above which sound does not pass through at an appreciable level, was also defined for each phone.
Playback and Transmission Frequencies of Cell Phones Margaret Coad
2.671 Measurement and Instrumentation
The frequency response of six different cell phones was measured to characterize their ability to play back and transmit the human voice. White noise was recorded by each of the six phones and played back into a reference microphone. The resulting signal was used to determine the frequency response function of each phone. For four of the phones, the same procedure was carried out for a phone call between two of the same phone. For recording and playback, the iPhone 4 had the highest cutoff frequency, 15,564 ± 708 Hz, while the LG enV 1 had the lowest cutoff frequency, 3,470 ± 343 Hz. However, for transmission, all phones had similar cutoff frequencies, close to 3,600 Hz, near the network standard of 3,400 Hz for telephone transmission. Thus, for sound transmission, all phones have similar sound quality, but for recording and playback, smartphones have higher sound quality than conventional cell phones.
Abstract Introduction
• For recording and playing back sound, smar tphones have h igher cu to f f frequencies, and thus better sound quality than conventional phones, most likely because they have more memory and are used to play music.
• For regular phone calling, all phones are equal in quality, with a cutoff frequency of approximately 3,600 Hz, due to the frequency filtering of the network at 3,400 Hz.
• On HD Voice networks, smartphones will be able to transmit sound with higher quality than conventional phones, as they are capable of recording and playing back sound with a cutoff higher than 7,000 Hz.
Conclusions
Dec. 3, 2013
Recording/Playback Summary Plot
References
Acknowledgements Thanks to Dr. Braunstein, Dr. Hughey, Prof. Leonard, and those who allowed their phones to be tested.
• Humans can hear sound in the frequency range from 20 Hz to 20,000 Hz. • To save digital storage space, cell phone networks transmit sound only within
a diminished frequency range, traditionally between 300 Hz and 3,400 Hz, represented by fstel, in the diagram below.
• Input sound is also filtered by the microphone and speaker of the transmitting and receiving phones, represented by fcin, fsin, fsout, and fcout.
• Speech filtered to below 3,400 Hz sounds muffled and thin, and certain
consonants such as “s” and “f” are indistinguishable from each other. • A higher range of transmission frequencies is desirable for intelligibility
and clarity. • A technology new to the US in 2013, called HD Voice, allows certain phones
on certain networks to transmit double the frequencies, expanding the range to 50 Hz to 7,000 Hz.
Methods
Cutoff Frequency: 11,110 ± 1202 Hz
Cutoff Frequency: 15,564 ± 708 Hz
Cutoff Frequency: 15,335 ± 94 Hz
Cutoff Frequency: 6,775 ± 634 Hz
Cutoff Frequency: 3,609 ± 166 Hz
Cutoff Frequency: 3,470 ± 343 Hz
Cutoff Frequency: 3,674 ± 65 Hz
Cutoff Frequency: 3,766 ± 146 Hz
Cutoff Frequency: 3,685 ± 278 Hz
Cutoff Frequency: 3,569 ± 32 Hz
Transmission Summary Plot
Recording/Playback Results Transmission Results
Traditional Network Cutoff: 3,400 Hz
HD Voice Cutoff: 7,000 Hz
1. Malcolm J. Crocker, Handbook of Noise and Vibration Control, John Wiley & Sons (2007).
2. Alexandra Chang, “How HD Voice Works to Make Your Calls Sound Drastically Better,” (2013), http://www.wired.com/gadgetlab/2013/04/how-hd-voice-works-to-make-your-calls-clearer/
3. Eberhard Hänsler, Gerhard Schmidt, Speech and Audio Processing in Adverse Environments, (2008), http://link.springer.com/book/10.1007%2F978-3-540-70602-1
Future Work • Explore other features of the frequency
response function besides cutoff frequency, e.g. dips and spikes at certain frequencies, and their effect on sound quality.
• Test phones capable of HD Voice to confirm larger frequency transmission range.
