OTHER TECH

Critical listening can be difficult, and it's easy to lose your bearings in a showroom filled with speakers. But if you stick to a few listening criteria, you will find the right speakers - and probably even have fun doing it.

• Above all, a speaker should sound natural. You know what your own voice sounds like (although you hear it differently from what others hear). Start speaking, then cup your hands megaphone-style around your lips. The unnatural sound you hear is coloration (some speakers actually impart a "cupping" sound), and likewise anything else that sounds strange is a sign of a bad speaker. Vocals should sound clear and natural, not forced. Musical instruments such as acoustic guitars should sound smooth and never harsh.

A speaker's tonal balance should be as neutral as possible. For example, listen to a jazz combo. You should be able to hear each instrument at a volume that's musically consistent with the others - that is, no instrument should seem overpowering. Finally, all the satellite speakers in a 5.1-channel system should sound more or less the same tonally.

Coloration is most audible, and annoying, in the midrange because the ear is most sensitive there. But also listen to the low end. The bass notes should be tight and musical, not just one-note thumping sounds. Listen to a bass-guitar line and make sure you can distinguish the individual pitches being played - bad speakers will mush different notes into one tone. And make sure the bass extends down to truly low frequencies. Listen to a movie soundtrack with a healthy explosion or two, and make sure the room rumbles. Also, listen to the high treble for the sparkle and "air" that give a sense of space and presence to music.

• Listen at both low and high volumes. Good speakers sound equally good at all listening levels. It's especially important to make sure the system can reproduce loud levels without undue distortion.

• Next, listen throughout the musical frequency range for detail. In a good recording, can you hear every musical instrument individually, or are they muddled together into a mass? Good speakers can provide incredible resolution, and you might even hear things in familiar recordings that you never heard before. If words like "nasal," "hollow," "edgy," "boomy," "thin," "chesty," "strident," "metallic," "dead," "smeared," "shrill," "fatiguing," or "wimpy" come to mind while listening to a variety of music, avoid those speakers.

• Use a recording with percussion or plucked strings to test the speakers' transient response - that is, the speaker's ability to respond to fast musical attacks. Percussive attacks of a hard-hit snare drum should be positively explosive, not weak and sluggish. An acoustic guitar should sound crisp, and the physical nuances of the performer's fingers on each string should be cleanly audible. Also listen to the ring-out as the sound of percussion or plucked strings decays - the reverberation (whether natural or artificial) should be smooth.

• Make sure the instruments are properly placed in space, even if they're panned between speakers. Stereo and multichannel sound creates a spatial sound field, so the images should be concise and definite, not vague or wandering. Similarly, listen to ambience - especially with 5.1-channel systems, which should create a realistic sense of immersion in a 360° sound field.

• Also check out dispersion - that is, the way a speaker distributes sound throughout the space in front of it. Some inferior speakers have such a small "sweet spot" that if you sit to one side or stand up or sit down, the tone changes dramatically. Make sure, for example, that the treble is consistent over a large area. Pay special attention to the sound of the center speaker, since it handles almost all of the dialogue on movie soundtracks and frequently the vocals on multichannel music recordings. Voices should sound natural over a wide listening area.

• Finally, close your eyes and listen for transparency. The perfect speaker system doesn't impose any sonic character of its own. That is, you should hear the recording, not the speakers. If you can imagine that the speakers aren't there, and that you're instead listening to live music, they've passed the ultimate test. - K.C.P.