Last week, I covered high-definition television (HDTV) specs such as the type, resolution and manufacturer.

This week, as promised, I'll tell you why I think that the refresh rate and contrast ratio are marketing ploys rather than important specifications.

The refresh rate is the speed at which your television screen refreshes the image. It is measured in hertz. The most common refresh rate is 60Hz. American television pictures are broadcast and recorded at 60Hz.

Some LCDs or LEDs go up to 120Hz, 240Hz or 480Hz. In theory, a faster refresh rate produces smoother images.

In actuality, that is not necessarily true.

Currently, 1080p with a 60 Hz response rate is the standard used for Blu-ray disks. No media, including broadcast TV, is available with a higher resolution or response rate. The 120Hz and 240Hz that you see in some HDTVs is pretty much a marketing ploy.

To perform at a higher refresh rate, they interpolate data between each of the 60 frames to produce additional frames - meaning, they add the data that they think should be there. While this can make the action look a bit smoother, it can also add an artificial feel to the video.

Contrast ratio is another specification that can be confusing to the average consumer. The contrast ratio is the difference between the darkest black and the brightest white that a screen can display. In theory, the higher the contrast ratio, the better the picture should be.

The problem is that there is no standard way of measuring the contrast ratio. So Sony, Samsung, Toshiba and others each measure the ratio any way they like. Of course, they each measure it differently, and each makes their televisions sound like the best. So basically, you cannot count on the contrast ratio you see on the box as being accurate.

If you are really interested in finding the television with the best contrast ratio, you will have to search the Internet for companies unrelated to television manufacturers that test each of the TVs with their own methodology.

You may have noticed that while today's HDTVs have wonderful picture quality, the sound quality is not as spectacular.

As televisions have become thinner and thinner, it is difficult for manufacturers to include speakers that deliver good sound. Some televisions use sound processing software to enhance the sound, but not many are successful in producing full, rich sound.

Unfortunately, the sound quality is something that is difficult to assess in a noisy store environment. You can get some idea of the sound quality by checking on the wattage of the speakers and the support that the television has for audio services, like Dolby Digital.

You can research reviews of the TV you intend to purchase to see what experts think, but even so, you can't expect to get phenomenal sound from a thin flat-screen television. If you want really good sound you will have to add a sound bar or hook up the television to some exterior speakers. Fortunately, you can buy a TV and add a sound bar later, if necessary.

When you do get your new TV home, be sure to access the settings and see what audio settings are available. Audio setting are usually limited, but there will be some available. The TV that I purchased recently came with Dolby Digital. However, when I accessed the settings, I found that it was turned off. Of course, Dolby Digital will only be available for transmissions that support it, but it will, at least, add slightly to the audio quality.

If you are looking at a new TV this holiday season, it is a good time to buy. Prices have never been lower, and there are no big new technologies that will change the television landscape for at least a few years.

The only exception to that will be the release of the Apple TV. Analysts are currently expecting that will happen in the second half of 2013. As you know, Apple has given us some unexpected and quite amazing products in the past. So it's anyone's guess as to what they will come up with next year.

Two other future technologies that have been creeping into the TV arena are OLED screens and Ultra HDTVs. I expect that it will be several years until these technologies are available and affordable.

OLED (organic light-emitting diode) has been poised for several years to infiltrate television. OLEDs are popular in cellphones and smaller devices. These screens have no backlighting. The pixels themselves light up. They are super thin and produce crisper, brighter images and sharper contrasts.

Samsung recently announced a 55-inch television, the world's biggest OLED set, but no U.S. pricing is yet available. Based on Korean pricing, it will be in the neighborhood of $10,000.

Ultra HD televisions, also called 4K televisions, have also been announced by Sony, Toshiba and LG. The Ultra HD television can display 8 million active pixels with a resolution of 3,840 by 2,160. That's about four times today's HDTVs. This technology won't be appearing in many living rooms anytime soon. There is no content yet available, and the 84-inch LG Ultra HDTV that recently went on sale costs about $20,000.

So there is little reason to wait. Now is a good time to buy an HDTV.

Contact Sandy Berger at sandy@compukiss.com.