Apple iPhone Cell Phone Review - Audio Quality

Alfredo Padilla
Published on June 29, 2007 Comment on this

Apple has been pushing the iPhone as a do-it-all device; it makes calls and is the best iPod ever. But it's still a phone, and the audio quality is the most important aspect of that. To test the audio quality of calls made with the iPhone we use professional testing equipment; a HATS (Head and Torso Simulator) that simulates the human head and ear and an electro-acoustic analysis program called SoundCheck. The combination allows us to analyze the quality of the sound that the iPhone sends and receives. For more details on how we test the performance of cell phones, see this article on how we test.

Sound Receive Frequency Response (7.58)

This test measures the frequency response of sound the iPhone receives when it is used as a handset. This represents what someone talking to you over the phone sounds like. The graph shows the frequency response of the phone in a blue line, with low frequencies at the left and high at the right. The red lines show the margins of the standards against which we test all phones. An ideal phone would produce a frequency response that moves right between the upper and lower margins. The iPhone performed exceptionally well in this test; the frequency curve of the phone was right between the limits, only coming close to them at a couple of points. This means that people talking to you over the phone will sound clear and bright, with well-balanced sound that should accurately represent what they sound like in person.

This compares well to other phones. Only two of our five featured phones (the Helio Ocean and the Treo 750) score higher than the iPhone, and they aren't that much better. Whatever Apple is doing with the small speaker inside the iPhone, they are doing it right.

UPDATE: Earlier versions of this review featured an incorrect score, caused by an error in interpreting the results. We have now corrected this mistake; Our apologies for any confusion caused.

Cell Phone	Apple iPhone (on AT&T)	BlackBerry 8800 (on AT&T)	Helio Ocean (On Helio/Sprint)
Score	7.58	6.99	7.88
Received Sound Frequency Response Graph (click to view)

Cell Phone	LG Prada (on AT&T)	Nokia N95 (on AT&T)	Treo 750 (on AT&T)
Score	7.42	6.46	8.24
Received Sound Frequency Response Graph (click to view)

Sound Send Frequency Response (7.57)

Sound send frequency response is the same measurement as above, just for the sound that is being sent from rather than received by the phone. The blue line again is the phone's performance, with our limits shown in red. The iPhone's performance in this test was very good; the frequency response only touched against the limits a little. The bass response (at the left side of the graph) is perhaps a little higher than we like to see; this could make your voice sound a little bit bassier than it really is. But overall, the sound quality is very acceptable. It scored almost identically to the Treo 750, slightly higher than the Nokia N95, and much higher than the BlackBerry 8800.

Cell Phone	Apple iPhone (on AT&T)	BlackBerry 8800 (on AT&T)	Helio Ocean (On Helio/Sprint)
Score	7.57	5.7	6.45
Received Sound Frequency Response Graph (click to view)

Cell Phone	LG Prada (on AT&T)	Nokia N95 (on AT&T)	Treo 750 (on AT&T)
Score	7.85	6.81	7.89
Received Sound Frequency Response Graph (click to view)

Handset Side Tone (0.8)

Side tone is how you hear your own voice when you are on the phone. So you can hear yourself speak, handsets inject a small amount of your captured voice back into the speaker. If they inject too much, your voice sounds too loud and you start whispering. Too much, and you start yelling. The ideal is about -18 decibels, but the iPhone seemed to have a problem here: we measured the side tone at -8.8 decibels. That's pretty high, so you might find yourself whispering a bit when you use the iPhone. This is comparable to the -9.43 decibels that we measured on the LG Prada, so it may have something to do with the thin, candybar style that the two share. However, nobody complained about how loudly we spoke on the test calls we made, so the low side tone may prove to be less of an issue than you might think. We'll be running more tests on this shortly.

Here is a chart comparing the iPhone's side tone to some other handsets.

Handset	Sidetone Measurement	Score
Apple iPhone	8.8	0.8
Blackberry 8800	16.72	8.72
Helio Ocean	22	6.45
LG Prada	9.43	7.85
Nokia N95	19.61	6.81
Palm Treo 750	22.2	5.8

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