Why does my microphone sound bad?

Technology has come a long way since the first telephone. Now we can watch the newest episodes of our favorite TV shows in 4K on a tiny piece of glass that we carry in our pockets. So why then, with all of this impressive tech surrounding our everyday lives, does your microphone still sound like crap? Well, we’re going to get into it, but first, let’s differentiate between two kinds of microphones.

First, there’s a microphone in the traditional sense: the kind that you envision when you think of someone performing on stage. As every venue has a different setup, this would be an impossible thing to explain in one article—but most issues with this type of mic can be solved with the correct equipment, or placement. Instead, we’re going to look at the other type of microphone, the one in your phone and headphones. Why do the microphones on some headphones sound better than others?

Editor’s note: This article was updated on April 16, 2020 to clarify some language.

Network coverage can determine call quality

First, there’s one obvious culprit we can point to that has nothing to do with your microphone, and that’s whether or not your phone even has service. This may seem obvious, but if you have a spotty network connection, then it doesn’t matter how good your microphone is because voice data is getting dropped along the way regardless. If you’ve ever done a video call with a crappy WiFi connection, you have a visual representation of what happens with your voice data over a bad connection.

Bluetooth is convenient, but it also sucks at data transfer

Similarly, you might also have to contend with the limitations of Bluetooth. Even if you have perfect service and coverage, the way that audio is packed and delivered over Bluetooth could potentially be another bottleneck. So what exactly is Bluetooth? Bluetooth is a low-power, low-bandwidth standard, and sometimes it falls short in transmitting data. While it’s come a long way since the early days, it just can’t keep up compared to things like Wi-Fi.

Then there are Bluetooth codecs. When it comes to transferring audio data between devices (like your phone to your headphones), one of the most important links in the chain is the codec. We have a full explainer already, but in short, a codec is how one device packages the audio data in order to send it to another device. If the receiving device doesn’t know how to open that package, then data gets lost as it just tears open the digital box. In a perfect world, all devices would perfectly package and open data, but our world is imperfect and data gets lost all the time. In fact, some of the most popular Bluetooth codecs including AAC, LDAC, and aptX all fall short on data transfer. Admittedly, this isn’t that big a problem for vocal frequencies. But what is a problem is how it affects the stability of the connection between the source device and your headphones.

As quality increases (more data), there is more strain put on the connection. Therefore, dropouts and stutters become more frequent. Some codecs are more stable than others when transferring audio, which means fewer dropouts when you’re on a call. You can see this clearly in the graph above pulled from our LDAC guide. LDAC 990 and 660 have better quality with correspondingly weaker connection strengths. The most stable? If you look all the way to the right of the graph are AAC and SBC. So if codecs determine how data is sent between devices, then bitrate determines how much data there was to begin with.

The way audio is converted into digital sounds is by a process called sampling. If you picture a sound wave, data is sampled twice per period, so a 44.1kHz sample that you might recognize as CD-quality will be able to reproduce notes up to 22.05kHz. AAC, which technically supports almost twice the number of samples at 96kHz, refuses to play nice with non-iOS devices.

It’s important to remember that the reason your microphone sounds bad probably isn’t just one thing. Every link in the chain from your headphones to the phone is probably good enough, but it just isn’t working perfectly. So while codecs dropping data probably isn’t the main cause of your poor microphone quality, when you add it to other parts of the chain it all starts to add up.

Diaphragm size matters

Finally, we’ve arrived at the microphone itself. When you picture a microphone, you’re probably thinking of something that looks like one of these. But obviously, stuffing one of these into your headphones isn’t possible. Instead, manufacturers used micro-electromechanical systems (MEMS) microphones instead, and these look very different. To simplify it significantly, MEMS microphones are a membrane sandwich. The top layer is a thin, charged membrane that is sensitive to slight changes in air pressure—while the bottom is a stiff plate perforated with holes.

As you speak, the changes in air pressure go through those tiny holes onto the membrane behind it, which moves in response to those changes. As the membrane moves the charge across the membrane changes slightly. Those changes can be measured and sent as data to the receiver, which then decodes the messages and plays it back via the speaker on the receiving end for the person to hear.

As you might imagine, the more surface area you have to work with (and pick up those very slight variations in air pressure), the more data is sent to the receiver for duplication. This results in your voice sounding better to someone on the other end. So the microphone that you’ll find on a pair of gaming headphones will usually have a separate arm with a large microphone attached to them. The microphones in a pair of true wireless earbuds, on the other hand, don’t have as much physical space to work with so they end up being significantly smaller and vocal quality suffers accordingly.

Too much background noise

Lastly, one reason you might sound bad is simply your surroundings. Some of the most important parts of vocals lie in the lower frequencies (<1kHz), which also tends to be around where most of the sounds around you lie, like passing cars, buses, and the low rumble of a jet engine on an airplane. When all of that is going on around you, the mic has a harder time picking up your voice. This is why some headphones come with noise cancelling microphones which work similarly to how ANC headphones work: try to reduce the ambient sounds it allows the microphone to pick up as much of your voice as possible. The Powerbeats Pro also implement a nifty trick to help reduce this problem. By using the accelerometers in the headphones the sensors inside are able to detect when you’re talking via the movement of your jaw. When it detects that you are not speaking, it actually turns off the microphone to help cut down on unwanted background noise during your call.

Related: What to look for in a microphone

How to fix your bad microphone problem

All in all, there are a number of factors that can contribute to poor microphone quality. You should, first and foremost, make sure that nothing is seriously wrong with your microphone if you’re experiencing vocal issues. Once you’re sure there’s no grain of sand in there from last August, you can start checking the other links in the chain. If everything checks out with your service provider, then the size of the microphone is the next logical step. Larger mics will usually sound better than smaller ones. Furthermore, you have to realize the limitations of Bluetooth. For the most part, they can handle the data transfer of your voice, but it’s not perfect and the biggest issue is dropouts and connection interruptions. If mic quality is important for you, we have a dedicated microphone score for each product we review so make sure to pay attention to that number.