Studies on the Perception of Bass in Four Concert Halls

The importance of bass to the overall sound quality in concert halls was highlighted at the opening of the Philharmonic Hall in New York in 1962 (Beranek, Johnson, Schultz, u0026 Watters, 1964). The hall provided almost no immediate lateral reflections, and bass could barely be heard on the stalls (Barron, 2009). The parenthetical comments brought up particularly the weakness of the cellos and the double basses. Apart from critique, this observation led to the discovery of the seat-dip effect (Schultz u0026 Watters, 1964; Sessler u0026 West, 1964). The seat-dip effect is the term assigned for the attenuation at low frequencies due to sound propagating almost parallel, that is, at near-grazing angles to the surface formed by the tops of the seat backs. The seat-dip effect is characterized by a main attenuation dip between 80 and 300 Hz, and an attenuation bandwidth that can extend up to 1 kHz.The seat-dip effect is objectively present in all concert halls with seats, but in many halls no noticeable lack of bass is perceived as such. In particular, the shoebox-shaped hall are generally characterized by a rich bass in the stalls (Schultz, 1965). This indicates that the seat-dip attenuation is corrected as the sound energy distribution in the concert hall develops over time. The lack of bass in the direct sound is compensated by reflections that contain the bass and arrive at the listener at nongrazing angles. This phenomenon is referred to as seat-dip recovery or correction.However, it remains unclear when the bass should arrive at the listeneru0027s ears. It was hypothesized that the seat-dip effect could be compensated by increasing the reverberation time at low frequencies (Schultz u0026 Watters, 1964; Barron, 1995). However, Bradley and Soulodre (1997) found that the perceived level of bass is not related to the reverberation time at low frequencies. More recent evidence suggest that the bass should arrive with the early reflections (Beranek, 2011; Davies, Cox, u0026 Lam, 1996; Patynen, Tervo, u0026 Lokki, 2013; Soulodre u0026 Bradley, 1995). Furthermore, Kahle (1995) suggested that sound energy arriving between 80 and 160 ms augments the perception of low frequencies. Additionally, Bradley and Soulodre (1997) linked the perceived level of bass to both the early sound level and late sound level. The phase of the reflections may also alter the perceived level of bass (Laitinen, Disch, u0026 Pulkki, 2013; Lokki, Patynen, Tervo, Siltanen, u0026 Savioja, 2011).It is scarcely understood how the seat-dip effect influences the perception of bass. Orchestral instruments that have their tuning range within the seat-dip attenuation range, such as double bass, tuba, and cello, may lack bass and articulation due to the seat-dip effect. For example, Bradley (1991) estimated that the attenuation of the double bass due to the seat-dip effect can be as much as 6 dB. Barron and Marshall (1981) observed that spatial impression is reduced in the presence of lateral reflections that contain the seat-dip attenuation. Davies et al. (1996) obtained a threshold of audibility for the seat-dip attenuation to be 5.7 dB in the 200 Hz octave band of the early energy over 0 to 40 ms. Although the seat-dip effect is generally considered to hamper the perception of bass, recent psychoacoustic research suggests that if the early reflections retain the bass, the lack of bass in the direct sound may actually enhance the overall perception of bass (Walther, Robinson, u0026 Santala, 2013).In addition to the seat-dip effect, the perception of bass in concert halls is affected by other factors, such as the residual absorption by the seats, walls, floor, and ceiling (Beranek, 2004, 2011). In general, hard thick surfaces absorb less bass than thin panels. Second, the vibrations of the stage floor have been proposed to augment the sound of the double bass and the cello connected to the floor via pins. So far, the augmented bass has been shown to be audible at the stage, but not among the audience (Abercrombie u0026 Braasch, 2010; Wulfrank, Lyon-Caen, Jurkiewicz, Brulez, u0026 Kahle, 2013). …