What Determines Audio Quality?

Matthew Cox | June 7, 2022 1:58 am

The sound quality of an audio device, whether it’s a portable Bluetooth speaker, a large PA system, a pair of reference monitors, or even earbuds/headphones, is affected by various electrical and physical components. 

Psychoacoustics suggests that what may sound good to one individual, may sound utterly jarring to another, this means that sound quality is, to an extent, subjective. In this article, we’ll be examining what affects the quality of sound (differentiating between poorly-represented audio vs clear and powerful quality), as well as what determines the properties of the sounds you hear through your speakers, headphones, or earbuds.

To evaluate the quality of the sound you hear, we’ll be following the signal path of the source material from the origins of the file/recording to the point it reaches our ears:

1. The Source Material

Audio file types

The first element that affects the quality of the sound you hear is, of course, entirely dependent on the quality of the content you’re feeding through the system. The first step of this process is evaluating the file format and how this affects audio quality. 

Digital audio files can be broken down into three categories:

  1. Uncompressed Audio Formats
  2. Lossy Compressed Audio Formats
  3. Lossless Compressed Audio Formats

Uncompressed Audio Formats

As the name suggests, uncompressed audio formats contain an accurate representation of the recorded content that has not been compressed. These file types are essentially the best for critical listening, however, they occupy loads of storage space on your device. Examples of these files include PCM (Pulse Code Modulation), WAV, and AIFF. Because these files are uncompressed, they are essentially the ‘best sounding’ file types.

Lossy Compressed Audio Formats

When audio files are compressed to preserve storage space on the disk, some compression processes sacrifice audio quality for disk space, these are lossy compressed formats, the most popular of which being MP3 files. MP3 files come in various file sizes, which can significantly impact audio quality. Additionally, streaming services offer varying levels of audio file quality.

The size of an MP3 file is measured in kilobits transmitted per second, ideally, you’d want a higher bitrate for better sound quality (I recommend a minimum of 1.411 kbps- CD quality) although 320 kbps can get you far enough.

Lossless Compressed Audio Formats

Lossless compression is the opposite of lossy compression- file size is decreased but the data remains undamaged. This means that these file types occupy less disk space while essentially performing to the standards of uncompressed audio formats. Common examples of lossless compressed audio formats include FLAC, WMA, and ALAC. 

If you’re unsure of what audio format is best suited to your needs, you can think of it like this:

  • If you’re capturing, processing, or critically evaluating audio content, uncompressed formats are highly recommended.
  • If you’re listening to music and want a faithful representation of the contents of the file and have some storage space to spare, go for lossless compressed formats. 
  • If you’re not too fussed and have a larger digital collection, lossy compressed formats would suit you best.

What if I’m not listening to digital files?

While it’s great to see vinyl listening making its comeback, many are falling victim to several delusions, the most popular of which being that it’ll make anything sound ‘better’. Now, it goes without saying that a vinyl record played through cheap speakers won’t sound much better than an MP3 file played on those same speakers, so you’ll need to start with a high-performing speaker system to truly appreciate the art. 

What Determines Audio Quality? 1

If you’re listening to records that were recorded and produced using analog gear (i.e. recorded and printed to tape) then yes, listening to that record on an analog medium makes complete sense. Listening to the latest pop or hip-hop album that was produced entirely in the box won’t sound any better on a fancy vinyl setup as it’s simply a print of digital information, so it’s more of an expensive gimmick, I guess. 

For vinyl listeners, the shape and style of your stylus will also affect what you hear. Since the grooves on the record are extremely narrow, you’ll find that more precise needles do a better job at recognizing these grooves and will, in turn, contribute to your music sounding more ‘real’. Also, poor needle technique can damage the tip of the stylus, resulting in static-type sounds during playback. 

At this point, it’s also important to note that poorly-produced material won’t sound any better on higher-quality systems or file formats. 

2. digital to Analog Conversion

Before the musical content reaches the amplifiers, speakers, and your ears, it first needs to go through a conversion phase where the binary information is translated to electrical energy, which electronic audio devices can understand. Every music-playing device has one of these converters, known as a DAC (Digital to Analog Convertor)

The quality of the DAC on your device is a crucial element affecting overall sound quality. Many audiophiles purchase and run dedicated DACs with their computers, televisions, and cellphones to get the most out of their listening experience. 

Most of the time, the onboard DAC on your device is good enough, but if you’re looking to enhance sound quality further, it’s definitely something worth checking out. DACs are available in portable forms, such as the AudioQuest DragonFly, or others designed for a more permanent installation, like the iFi Zen DAC V2

3. cabling and Connectors

XLR Cable Connectors Closeup

Once your source material is now an electrical signal traveling between audio devices using analog or digital cables, the quality of these cables and their connectors can impact what you hear. 

If you’re running signal over short distances, you shouldn’t need to stress about this too much. However, higher-quality cables and connectors will prove to last longer than the stock cables and will certainly reduce the amount of unwanted noise you could potentially experience. If you’re looking to upgrade your cabling, my favorite brands I seriously recommend include Neutrik, Amphenol, and Kirlin.

4. Bluetooth codec (if applicable)

If you’re streaming audio over Bluetooth, or any other wireless technology, there are other factors that can impact sound quality, primarily the Bluetooth codec in use. 
Bluetooth has seen several updates through the years, and different codecs excel in different spheres. We have a guide on Bluetooth codecs for you to check out, but for now, it goes without saying that a newer, faster, and higher quality codec should be used if you’re expecting high-fidelity audio.

What are the best Bluetooth codecs?

I favor AptX Lossless/Adaptive codecs, which offer CD-quality sound, and if you’re using an Android device, LDAC is also a good option.

5. speaker build quality & components

Speaker Driver Closeup

In the final step of our signal chain, we need to take a look at the actual speakers themselves, as they are essentially the most critical aspect of this whole process: A great pair of speakers will still sound pathetic when low-quality file formats are used, and a low-quality pair of speakers will only get you so far, no matter how much you spend on DACs, cabling and external drives to store your uncompressed music collection. 

Assuming you’re dealing with a well-built speaker system made from high-quality components, we can now look at how this speaker will sound based on its physical attributes:

The Speaker Drivers

The drivers that vibrate to deliver the sound going into the system are an incredibly important part of the process. Speaker drivers can be made from various materials, each with its own acoustic properties. For example, tweeters made from light metals seem to perform better when replicating higher frequencies, as these materials allow them to vibrate fast while retaining their rigidity, unlike paper or plastic cones. 

Build quality aside, the driver configuration also greatly affects speaker performance, more specifically, for your intended needs.

The design of speaker drivers and the relation to sound quality is a rabbit hole in itself, and even just the structure of the driver coil can have an effect on the overall sound quality experience.

If you’re looking to play bass-heavy music through your system, you might feel a small 8-inch speaker doesn’t sound ‘good’ to you, but it’s actually just not designed to reproduce ultra-low frequencies. 

The Speaker Cabinet

The enclosure material also dramatically affects the way the speaker will sound, as different materials co-operate with moving airwaves better than others. Most speaker cabinets are made from different types of plastics and woods, each with its own sonic properties. 

While a plastic speaker cabinet is more cost-effective and lightweight and can be molded to specific shapes/designs, you’ll find these enclosures can produce some nasty resonances, which can be an audiophile’s worst enemy. 

Wooden enclosures are preferred, and while cheaper woods are mostly used, it’s not too difficult to find some really exotic enclosures, though they might become expensive and heavy. 

Lastly, speaker placement is also incredibly important when it comes to getting the most out of your sound system. This can become quite involved, so you can take a look at our speaker placement guide here for some more in-depth information. It’s also worth reading up on how your listening level can affect a speaker’s performance.

What about headphones & earbuds?

Headphones and earbuds work on many of the same principles, as they’re also just a series of speaker drivers, housed within a cabinet, and connected to your source material via wired or wireless connections. Audiophiles and sound engineers favor open-back headphones as they provide a more accurate representation of the source signal. 

The construction of headphones will impact the impedance and sensitivity of that device. Headphones that have higher impedance will require an external amplifier in order to get the most out of them as they need more power to drive them. Most source devices can easily cater for headphones of up to around 50-80 ohms but after that point investing in a headphone amplifier can really increase the sound quality of your product.

The performance of a pair of headphones or earbuds is affected by several factors, the first of which is the physical properties of the device: Earbuds that fit more comfortably in your ears will reject much of the outside noise, thus providing a cleaner performance. The number of drivers found within a pair of earbuds or headphones also greatly affects the device’s frequency response, this is why a pair of in-ear monitors that run 7 drivers a side will sound exponentially better than a pair of Apple AirPods, for example. 

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Author: Matthew Cox

A sound engineering student and musician, Matthew enjoys writing and performing music, working in the studio, and geeking out over anything audio-related.

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