The tone varies, even among pianos of the same make and model. No matter what its size or cost, any good piano should provide a wide range of tones, from soft and sweet to loud and bright. The tone should be even from the lowest to the highest notes. Most of all, it should sound musical.
What does the perfect piano tone sound like? There is no single answer because everyone's taste varies. Also, certain tonal characteristics are more suited to specific styles of music. A bright, lively tone might be best for jazz, whereas you might prefer a rich and dark sound for Beethoven's music. There are many different sizes and models of piano available in the marketplace; you chose your piano because it sounded good to you.
But a piano's tone changes with use. As the hammers wear and compact, the tone often becomes too bright and harsh, robbing the pianist of the ability to produce a sweet sound. As parts wear, the regulation (adjustment of the mechanical parts that transmit motion from the fingers to the hammers) becomes uneven, and the pianist loses control over volume and tone. This is most noticeable in quiet playing. A delicate pianissimo passage becomes very difficult or impossible to play, and some keys may not sound at all if played very lightly.
Aging of the piano's strings and structure also can diminish its tone.
Other factors that affect the sound you hear from your piano are:
ROOM ACOUSTICS -- Hard shiny surfaces such as windows and bare floors reflect high frequencies, making a piano sound bright and loud. High ceilings or large adjoining rooms add resonance. Rugs and upholstered furniture soften the tone and add warmth.
THE LID -- Both grands and verticals sound louder and brighter if the lid is opened.
YOU -- Your ears are sensitive and will perceive sound differently if you have spent all day in a quiet office or at a loud construction site.