Hi all, Recent discussion of mics in or near the bell leads me to post the following conjecture. I've been thinking about this for a while, but I'm a seismologist, not a recording engineer. Any expert comments appreciated. Anyone willing to try this?
-- An empirical transfer function for improved horn recording It is widely agreed that the best microphone placement for recording horns is in front of the player(s). This is because our concept of horn sound includes the effect of the hand in the bell and reflection from the wall or other objects behind the player, as well as the effect of the player him/herself on the radiated and reflected sound. All of this determines "horn sound". At the same time, recording engineers often prefer to place microphones immediately behind the horn player, often only a few inches from the bell. This enables the engineer to isolate the horn player's sound, allowing mixing, filtering, or editing of the horn player's sound independent of other instruments. The problem is that this results in a sound that is harsher (richer in higher harmonics), more like a trombone than our concept of "horn sound". In principle, it should be possible to record a single horn player with microphones placed both in front (perhaps at the front of the stage) and immediately behind the player. The player should play notes covering the full range and dynamics of the horn. The rear recording is then deconvolved from the front recording. In the frequency domain, the complex spectrum of the front recording would be divided by the complex spectrum of the rear recording, resulting in an empirical transfer function of all of the acoustic effects occurring between the horn player's bell and when the sound arrives at the front of the stage. Such an empirical transfer function is not perfect. It will require smoothing, and should probably be constructed as an average of several players, instruments, rooms, etc. The resulting transfer function could be applied, just as any linear filter is applied, to recordings made immediately behind any horn player's bell, including recordings made behind a section of horn players. The result would not be as good as a single microphone in front of the player(s) at the front of the stage, but would likely be much better than the harsh recordings made directly behind the player. Note that it is not necessary to understand all of the acoustics of the musician, the instrument, either internally or its radiation and directivity, the hall or the recording devices. The empirical transfer function is simply an average representation of the effect of those portions of the acoustics occurring between the bell and the front of the stage. -- Jeff Barker Associate Professor of Geophysics, Binghamton University, Binghamton, NY Amateur horn player, Binghamton Community Orchestra and Southern Tier Concert Band (among other groups) _______________________________________________ post: [email protected] unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/archive%40jab.org
