It kinda depends. If we’re talking about normalization of an audio demo to create what is called “apparent loudness”, it might be somewhat deceptive and hence abnormal.
The human ear’s sensitivity to sound rolls off at both the low end (bass) and the high end (treble) as the sound level decreases. This is commonly referred to as the Fletcher-Munson effect and the curve describing the phenomenon is called cleverly enough, the Fletcher-Munson curve. So put simply, at higher average levels, music tends to sound better whether it is or not. Tighter more restrictive dynamic range tends to sound brighter and tighter. Just ask the chief engineer at any radio station trying to boost ratings.
Yada, Yada, Yada, right? Well not so fast. If a music demo of a tune on a website is normalized, will that change the sound or more importantly, the propensity of the listener to buy the aforementioned tune over tunes demoed on other sites which have not been normalized? Yes on both counts. How has the sound been changed? Just look at the waveform displayed by many library websites. If it appears flattened, it likely has been normalized. And of course, your ears are your best guide. Ear splitting highs just increase listener fatigue.
Shouldn’t processes like EQ, Compression, Normalization, etc. be within the purview of the end user rather than the purveyor? We at CSS Music say Yes! Rather than futz with the sound (some say “step on”) we suggest that when you listen to our demos that you crank the level up about 3db or better yet, do your reviewing using a high quality headset.
End of Rant.