You just bought that brand new 50 inch state of the art LED TV. The picture is fantastic and it includes all the newest Smart TV features. You get it home, plug it in and go through all the set up in the manual. You turn it on to watch one of your favorite shows or movies. The picture looks wonderful, but the sound is awful. The audio is garbled and the dialog is virtually impossible to make out. After fiddling with all the built-in audio settings you finally give up and either take it back or decide to live with it.
There are alternatives, some cheap and some not so cheap, which I will discuss in a bit but first, let's take a look at the root cause of the problem.
Why is TV Audio so bad
There are 4 main reasons for bad audio quality on today's TVs. Most of these have to do with what makes these TVs attractive in the first place. One of the marvels of today's LED TVs is how thin and light weight they are. Can you imagine hanging a 50in CRT TV on the wall? However, the thinness of the TV forces some major compromises in the quality and design of the speaker subsystem.
First, the speakers are much smaller in today's TVs than in the older CRT TVs. The elements are
typically rectangular (1inch x 3inches) with very small displacements. Sound is made by moving a speaker element back and forth (pushing the air). This is called displacement. Displacement is especially important for generating the low frequencies. The more displacement a speaker has, the lower the frequency it can generate. A male voice has a fundamental frequency between 85 Hz and 180 Hz, while a female voice has a fundamental frequency between 165 Hz and 255 Hz. Because of the physical size of the speakers and their limited displacement, the natural frequency response of a TV speaker cuts off somewhere around 200 Hz. Thus, you are not hearing or barely hearing the voice fundamental frequency. What you do hear are the harmonics (multiples of the fundamental frequency) which are lower in amplitude and decay away; and the only reason you hear any dialog at all is because of these harmonics. When your ear hears these harmonics, your brain believes it also hears the fundamental though at a lower volume. Which is why the dialog sounds muted.
Not only are modern TV's thin, but they also have very thin bezels (the picture frame around the display portion of the TV). Because the bezels are so thin, there is no room to place the speakers, so the speakers are either placed in the back of the TV, or they are placed facing downward along the thickness dimension of the TV. This directs the sound away from the viewer and either bounces it off the wall or off the TV stand. During these bounces, the frequencies can cancel themselves, reinforce themselves or interact in ways that cause the audio to be distorted. In the old days, the TV design had an extended bezel below the picture tube where generally the speakers were placed. The speakers were placed so they faced the viewer, thus minimizing the reflections (bounces) giving much clearer audio.
Low Power Drivers
Because of speaker size, cost, and power dissipation considerations, the output power of the speakers in today's TVs is generally between 5Watts to 10Watts per channel (stereo channel). How loud this is will depend upon the speaker efficiency, and how far away the viewer is. The recommended viewing distance for a 50in HDTV is around 8-10 feet. Considering the typical TV speaker and the recommended viewing distance, the maximum loudness would be about equivalent to a loud radio in an average room. However, that is with the speakers pointing at you. With the speakers pointing down or away from you, the loudness would be less and the audio in the TV would appear to you to be underpowered.
Bad Audio Algorithms
The TV manufacturers try to address some of these issues by using sophisticated audio processors to compensate for the deficiencies in their speaker designs. The algorithms executed by these processors are used to provide bass enhancement or virtual surround sound and even voice band enhancement. However, the algorithms that are being used are far from optimal. The algorithms being used do not compensate for changes in the source material, so that things may sound great on one TV channel or show, but sound terrible on another. The algorithms are static when they need to be dynamic so they can respond to changes in the source content. Some of the algorithms are just pieced together. Rather than looking at the whole audio experience, each algorithm is optimized for it's own performance. Optimizing the components of a subsystem rarely leads to the optimization of the entire system. For example, if you optimize for bass enhancement, you wind up compromising the surround sound algorithm and conversely, if you optimize the surround sound algorithm, you will compromise the bass. Unless these algorithms are tuned so that the entire result is optimized, the audio will not improve. Thus, in the end, unless properly tuned (which rarely happens) these algorithms do little to solve the problem.
What solutions are available?
There are several solutions available ranging from free to expensive. Each has varying degrees of affect on the problem.
The Free Solution
The free solution is to adjust the audio settings in your TV. Go into the setup menu on your TV and select the audio setting panel. Then turn off as many of the settings as possible. For example, turn off surround sound, turn off bass enhancement, turn off Dolby, etc. If there are bass and treble controls, make sure each is set exactly the same typically around 50% but you could go as high as 100% each. Turn off any thing that says level sound and night mode or commercial mode. If the TV has any kind of an equalizer, set it for flat. This gets your TV into a baseline setting. If the dialog is still not to your liking, then chances are none of the other settings will help it. If it improves, then you can go back into the settings and adjust the bass and treble. Turning on the other effects will not do anything for the dialog, so you should leave them off.
The Sound Bar
If none of this works and you have downward or rearward facing speakers, then the next solution will cost you money. It is a sound bar. A sound bar is exactly what the name says, a bar with multiple speakers to the left and right. The bar gets it audio from the TV through a variety of connections. The speakers are generally of better quality than a typical TV speaker and the bar has it's own power supply and internal amplifier so that it can get louder than your normal TV. Best of all, the speakers are forward mounted; pointed directly at you.
There is much variety in sound bars, some with subwoofers, some without. Some that are multichannel and some that are not. The best bang for the buck, however, are either the 2 channel (2.0) or 2 channel with subwoofer (2.1) sound bars. Multichannel sound bars really do not give you the same results as a full multichannel home theater system. The reason is that in a multichannel home theater, you place the speakers around you so that you get the full sense of sound placement. A multichannel sound bar, however, still has all the speakers in front of you, so that while you get all the channels, you lose the sense of placement. One thing to consider is that very few broadcasts are multichannel. They are predominately 2 channel. So if your primary use of the TV is broadcast, then a multichannel system won't do much good.
The 2 channel or 2.1 channel sound bars all come with various software algorithms that enable enhancements (bass enhancement, simulated surround sound, etc). If you are primarily interested in dialog, then in the sound bar set up panels, disable all of these for the same reasons I mentioned above for your TV. The processed audio, while better than in a TV, can still be muddy. Once you have acceptable dialog, then you can make adjustments with the other settings if you so desire.
Using a subwoofer can be good and bad. Proper use of the subwoofer gives more richness to the audio. Your ear expects to hear these frequencies and if they are not there or are muted, it almost feels like there is a hole that needs filling in. Be cautious, however. The subwoofer typically has it's own amplifier and volume control so that you can adjust it separately from the main speakers. You need to keep the subwoofer volume down fairly low (remember it is just filler). If the sub-woofer volume is set too high it will dominate the other frequencies and will sound horrible. If you want to be knocked out of your chair with that special effect explosion, then be prepared to lose the dialog. Adjust the volume in small steps until you achieve the desired effects.
The Home Theater
There is a third option to improve the audio on your TV, but it is typically more expensive and involves much more setup. That option is the home theater system. Because of it's complexity and expense, I won't delve into that discussion here.
The audio from today's TVs is substandard because of the use of small underpowered speakers, their placement (away from the listener), and the use of sub-optimal audio algorithms. To improve the quality (especially of the dialog), the consumer can adjust the TV itself; removing any audio special effects, buy a sound bar (also removing any audio special effects), or buy a home theater system. The sound bar represents the best cost/performance/complexity tradeoff for the consumer.
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