One of the primary concerns of a classical music concert artist is the adequate projection of the sound in the concert hall. In fact, if the sound doesn't reach the listener in a clear and well perceived manner, even the finest performance, rich in detail, will be poorly communicated, or perhaps misunderstood by the public.
Many great performers, however, are much more concerned about the perfect setting up of their instrument, and much less about how the sound reaches the listener in a given hall. It is, of course, true that every hall has different acoustic characteristics, which may sometimes radically modify the projection of the sound. Also the perception of the speed and the clarity of the details are, therefore, widely influenced by the reverberation and equalization of the hall, whose acoustics can soften the sound (sometimes, though, at the expense of clarity of detail), or make it harsher or inflate it disproportionately. Often an orchestra or soloist on tour has just a few hours to rehearse in a hall, and the time available for them to test the acoustic response is very limited. What can we do, then, to optimize the projection of the sound in a short space of time?
In my experience, I have ascertained that it is always very useful to listen to the instrument while sitting in the auditorium, that is to say asking a colleague to play in our place. In this way we will, of course, get only a general and not so precise impression, since every musician has a different way of playing, but it will nevertheless serve to give us a rough idea of how the sound “travels” in the hall and how it arrives, which sometimes changes radically depending on which part of the hall you are listening from.
At this point, once we have returned to the stage to play, it will be easier for us to imagine listening to ourselves from the audience, while we are playing. If, in fact, we try to imagine placing our point of listening not on the stage where we are, but further away, in the middle of the auditorium, it will be easier for us to think of projecting the sound in the distance, and also to manage the transmission time of the sound and the resonances depending on the acoustics of the hall. In reality, every hall could be seen as a large sound box, and thus an actual part of the instrument: the acoustics of the hall transmits the sound from the instrument to the listener and is, therefore, an indispensable link in the chain of live music communication.
Also in our daily practice, even though in a very small room, it can be helpful to get used to "listening from afar”, as if we were sitting in an imaginary auditorium, and forcing ourselves to produce a sound that could travel easily through the air, and arrive far away. This also depends on technical factors: by using a long lever, like the whole arm and not just the finger, the sound will acquire a greater depth.
To sum up, then, it is important to “listen” to the hall where we are playing, and not only to our own instrument. The outcome of a performance is an alchemy between our expressive ideas, the response of the instrument and the intervention of the acoustics, and only by taking all three of these aspects into due account can we best express our musical intensions.