Our Sound Quality Score and Tests
Sound quality is how accurately audio is reproduced as intended by the producer/engineer. Our reference for TV sound quality is the loudspeaker. The ideal TV sounds like the ideal stereo speaker setup in the ideal room.
From music to movies, video games and TV series, audio is arranged/mixed in a studio to have a distinct sound. Accurate TVs are able to reproduce that sound as intended. Though some listeners might prefer a more hyped bass or treble, in our tests we consider an accurate and neutral reproduction to be more desirable. Most TVs have a only a mediocre sound quality and a dedicated speaker setup or soundbars are recommended to those who want a good sound reproduction.
For our sound quality score, we evaluate the frequency and distortion responses of the TVs at multiple intensity levels.
Frequency response is the most important part of an audio reproduction. For the most part, the perceived subjective sound quality of a speaker can be predicted from its frequency response1,2,3,4. It describes how accurately a system reproduces each frequency of an audio content, in terms of amplitude. A TV with a good sound has an extended bass, a neutral frequency response and can reproduce the audio content at high intensity levels without compression or pumping artifacts. That is, if the music was mixed to sound bass-heavy, a good TV will reproduce it as bass-heavy. Conversely, if the content is supposed to sound bright, a TV with a neutral frequency response will reproduce it as bright and at loudness levels proportional to the size of the TV and its optimum viewing distance.
Having a good frequency response is important for all TVs, regardless of their use case, since it has the largest effect on their perceived sound quality. However, the role of sound quality is more crucial for some use cases such as watching movies, music listening and gaming, compared to watching the news or TV series where sound quality may not be as crucial. Most TVs available today suffer from lack of bass, low volume, and pumping and compression artifacts under heavy loads. Also, since the acoustics of the room in which the TV is setup plays a big role in its frequency response performance, it is important for TVs to have a room correction system. Some TV manufacturers are starting to implement such systems in their TVs, however, their performance effectiveness is not quite high and leaves more to be desired.
We measure the frequency response of TVs from 20Hz to 20KHz, at three intensity levels of 70dB SPL, 80dB SPL and Max SPL (i.e. the TV is set to maximum volume). The test results are then processed to calculate low-frequency extension (LFE), frequency response error (at 70dB, 80dB, and Max SPL), dynamic range compression, and maximum loudness achievable by the TV.
Distortion is any change to the original signal by a system. In other words, it is an unintended frequency, generated by the TV, which is dependent/related to intended frequency fed to the system. It is also worth noting that distortion differs from noise by being dependent/related to the original signal, whereas noise is a random external/unrelated signal added to the original signal.
In sound reproduction, distortion is considered a flaw since it reduces the accuracy of reproduction by generating frequencies that were not included in the original content, which was created by the producer/engineer. This colors the sound and could make the music sound impure, harsh, or muddy.
It is important to have a TV that produces low amounts of harmonic and intermodulation distortion when a clean and pure sound reproduction is desired. For example, in music listening applications, and especially when there is a preference for a clean and uncolored reproduction, like in classical music. Or in situations where the sound reproduction is excepted to be full-spectrum and at loud volumes, like when watching an action movie in a large room, since TVs generally produce more distortion under heavier loads.
However, since moderate - and even in some cases - high amounts of harmonic and intermodulation distortion is not very audible to humans, most TVs should be considered good-enough in this regard. Except for extreme cases, their THD and IMD performance shouldn't be a deciding factor. Audible levels of distortion tend to deteriorate the sound reproduction by making it muddy, colored, or harsh.
We perform harmonic and intermodulation distortion tests for TVs at 80 dB SPL and at Max SPL (i.e. the TV is set to maximum volume).
What is not included
A few elements that you could care about are not included in the score:
- Audio format (Compression, bitrate, digital, analog, etc...)
- Listening window (how well a TV sounds off-axis)
If you feel there is an item missing that should be included, please let us know in the Q&A section.
Sound quality is how accurately audio is reproduced compared to the original audio arrangement. An ideal TV's audio reproduction sounds like a pair of loudspeakers in a room and is balanced and accurate to the source material as it was intended to be heard. For sound quality, we evaluate the frequency and distortion response of TVs at multiple intensities. TVs that score highly for sound quality will sound great no matter what you are listening to. However, most TVs tend to have a mediocre sound quality and usually a dedicated speaker system or soundbars are recommended to those who want a good sound reproduction.