Apple iPhone 3G Cell Phone Review - Audio Quality

We were very happy with the Apple iPhone 3G's performance on our audio tests. Othe reviews have mentioned that audio quality has improved, but our tests prove that it has indeed taken a big step up over the previous generation.

General Audio
However many fancy features a phone has, the fundamental job of the phone is the same; to allow you to make and receive phone calls. That's why we do extensive testing of the audio quality of cell phones, using a high end electroacoustic testing system with a Head and Torso simulator and an electoracoustic analysis software package called SoundCheck from the Boston-based company Listen, inc. This allows us to analyze the sound quality of the phone in depth; while other reviewers just make a few calls to their friends and ask how they sound, we look at the frequency response and sidetone of a phone in a scientific fashion. For more information on how we do our audio testing see this article

Sound Receive Frequency Response (8.13)
In this test, we examine the sound that the phone outputs, such as someone talking to you in a phone call. We look at the frequency response of the phone, and if the phone has performance that falls within the limits that a group of industry experts have set for acceptable performance. These limits are indicated by the red lines on the graph; a good phone should fall within these. The frequency response of the iPhone 3G is shown by the blue line, going from low frequencies on the left to high frequencies on the right.

As you can see, the iPhone did well here; the frequency response is within the limits for most of the range, only touching agisnt the limits at the high end. This means that voices over the line will sound clear and natural, with no bias to one frequency that could make voices sound odd. In fact, the frequency response has bumps in all the right places, with a slight increase in frequency response in the range of 4-7Khz, which is what the limits calls for (the bump in the top right side of the graph). This is important because this area is critical for making voices understandable, so it is good to see that this area has a slight bump. The iPhone 3G beats out most of our comaprison phones here; only the BlackBerry Curve and the origional iPhone had higher scores. There is also a serious improvement from the origional iPhone here; that had an annoying dip in response in exactly the same critical range that the new iPhone has a pleasant bump. 

Cell Phone	Apple iPhone 3G	Samsung Instinct (on Sprint)	LG Dare (on Verizon)
Score	8.13	7.25	7.73
Received Sound Frequency Response Graph

Cell Phone	Nokia N95 w/ US 3G (on AT&T)	BlackBerry Curve 8320 (on T-Mobile)	Apple iPhone (on AT&T)
Score	7.90	8.30	9.17
Received Sound Frequency Response Graph

Sound Send Frequency Response (8.34)
Here we look at the quality of the audio sent by the iPhone, such as you speaking into the phone. How well does the iPhone pick up and transmit your voice? Pretty well, according to our tests; the graph below shows the results of our examination of the frequency response for sent audio quality.

Again, we look at the performance to see how well it falls within the limits set by a group of international telephone experts, and the iPhone 3G did well here. The frequency response is well within the limits, meaning that the iPhone does not overly exaggerate or supress any of the wide range of frequencies that your delightlful, lilting voice contains. Our only concern is that the response drops off slightly at the higher frequencies, which could give your voice a slightly clipped quality. But overall, the iPhone did very well; if your voice sounds awful over the iPhone 3G, it's probably because it sounds that way in real life.
The iPhone 3G did better than most of our comparison phones here again; it beat the Samsung Instinct and the LG Dare by a significant margin. Both of these phones had some nasty bumps in their response curve, indicating that some frequencies came across as being stronger than others. The iPhone 3G didn't have this issue; the response was pretty uniform across the frequency range. And again, there is also a significant improvement from the original iPhone; the response is much smoother, which translates to a more accurate reproduction of your voice. 

Cell Phone	Apple iPhone 3G	Samsung Instinct (on Sprint)	LG Dare (on Verizon)
Score	8.34	6.75	6.74
Sound Sent Frequency Response Graph

Cell Phone	Nokia N95 w/ US 3G (on AT&T)	BlackBerry Curve 8320 (on T-Mobile)	Apple iPhone (on AT&T)
Score	6.51	7.51	7.58
Sound Sent Frequency Response Graph

Handset Side Tone (9.37)
Side tone is how cell phones deal with the problem of being unable to hear your own voice. You judge the volume of your voice by how loud it sounds in your own ears, but that doesn't work if the ears are blocked by a big old cell phone, so you start talking louder without realizing it. This explains why people talking on old cell phones often shout (although that could be because they are just idiots). Modern cell phones deal with this by injecting a small amount of your own voice back into the speaker so you can judge your own voice level; this is called sidetone. We test sidetone against the -18dB level that the same group of experts that set the limits for our other tests reccomend, and again, the iPhone 3G did an excellent job here. We measured the sidetone of the iPhone 3G at -18.76dB, just a touch off the recommended level. This means that the iPhone 3G does a great job of capturing your voice and passing it back to you, so you can hear yourself speak. If you end up shouting down the phone, it won't be the iPhone's fault.

Side Tone

Above is a chart that compares the performance of the iPhone against other phones. As you can see, it did slightly better than most other cell phones as the measured sidetone was closer to the desired level. Although these differences are minor, it is an important aspect of cell phone performance, and the iPhone 3G does a great job. 

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