Acoustic Bulletin

Room acoustics blog

Good acoustics as an extra source of income in restaurants

by

Internoise 2019, Madrid

It’s all about money! Juan Negreira held a really inspiring presentation at Internoise 2019 – about how a room acoustic intervention in a restaurant lead to better income. Below are his findings and discussion and if you want to know more about the project and get access to the original paper, you can contact Juan at [email protected].

Spain is world leader in number of bars and restaurants

Bars and restaurants are deeply rooted in the Spanish culture. They are places identified with socialization, friendship, relax; and factories of opportunities and inspiration. Spain is the absolute world leader in number of bars and restaurants: one for each 175 inhabitants (i.e. almost 280,000 establishments).

Unfortunately, noise levels there are often of such extent that having a conversation with the people one goes with becomes nearly impossible without having to strain one’s voice, which hinders acoustic comfort and thus complaints by the clientele arise.

A case-study

A case-study of a restaurant that Ecophon Spain performed in Madrid was presented last June 16th at Internoise. The restaurant, which initially complied with the Spanish regulations in terms of reverberation time (the norms require 0.9 seconds averaged in the mid-frequencies, i.e. 400 Hz-1250 Hz, for unoccupied conditions), the customers often showed their discontent with the acoustic environment numerous times.

Fig.1 – Cre-Cottê’s dining room both pre- (upper left) and post- (upper right) intervention, and drawing of the panels installed (bottom).
Fig.1 – Cre-Cottê’s dining room both pre- (upper left) and post- (upper right) intervention, and drawing of the panels installed (bottom).

Therefore, the restaurant took action and carried an acoustic refurbishment by installing absorbing material (free hanging units –Ecophon Solo® and also ceiling panels glued onto the soffit –Ecophon Master SQ®, see Fig.1). The installation was done without any interruption in the business´ normal activities. To evaluate its effect, three actions were taken:

  1. A subjective evaluation of the customers employing questionnaires both pre-project (February 2018, 194 participants) and post-intervention (April 2018, 182 participants), see Fig.2.
  2. Measurements of different acoustic parameters were performed according to UNE EN ISO 3382 (parts 1 and 2) before and after the refurbishment.
  3. A financial data analysis.
Fig.2 – Survey used for the subjective evaluations both pre- and post-intervention.
Fig.2 – Survey used for the subjective evaluations both pre- and post-intervention.

The investigations performed by analyzing the acoustic measurements and the customer opinions (surveys) both before and after the intervention showed the following conclusions:

  • Acoustic measurements showed improvement (after the acoustic intervention) in terms of reverberation time, speech clarity, definition, sound strength and equivalent sound pressure levels (see Fig.3).

    Fig. 3 – Results of the acoustic measurements before (in red) and after (in green) of the acoustic intervention: reverberation time (upper left angle), speech clarity (upper right angle), sound strength (lower left angle), and equivalent sound pressure level (lower right corner).
    Fig. 3 – Results of the acoustic measurements before (in red) and after (in green) of the acoustic intervention: reverberation time (upper left angle), speech clarity (upper right angle), sound strength (lower left angle), and equivalent sound pressure level (lower right corner).
  • Dissatisfaction with overall noise and conversation with other guests improved amid the clientele after the refurbishments, as showed by the surveys.
  • No marked change in quality of food, service, ambience or value for money. However, it should be pointed out that the satisfaction was already very high pre- and post-refurbishment.
  • The on-line ratings showed an improvement in the platform El Tenedor (see Fig.4). This is a crucial aspect nowadays, as 90% of consumers read online reviews before visiting a business.

    Fig.4 – El Tenedor (Spanish version of The Fork) screenshots online ratings before (left – 5th April 2018) and after (right – 23rd October 2018) the refurbishment.
    Fig.4 – El Tenedor (Spanish version of The Fork) screenshots online ratings before (left – 5th April 2018) and after (right – 23rd October 2018) the refurbishment.
  • Over the 6 months following the refurbishment, the income increased by circa 11% compared to the same months the year before (see Fig.5), i.e. across the year there is a potential, in this case, for increasing the yearly income with slightly more than one extra month. Note that the prices in the menu were not varied between the both years analyzed (2017 and 2018).
    • The total cost of refurbishment for this particular case had a payback period of around 4 months (calculated on the benefit, not the revenue; and assuming the conservative costs/gross margin repartition 50:50). From then on, the invoicing is likely to improve just but improving the acoustic atmosphere.

      Fig.5 – Invoicing deviation in 2018 (in percentage) respect to the same month the year before (i.e. comparison before and after renovation).
      Fig.5 – Invoicing deviation in 2018 (in percentage) respect to the same month the year before (i.e. comparison before and after renovation).

Short payback period

The simple acoustic solution undertaken (in terms of installation time, cost and influence in the activity of the business) showed to significantly improve both customer satisfaction and revenue, with a payback period of less than a couple of months. The latter refurbishment could eventually be improved by adding other type of products (wall panels in the dining room, acoustic solutions for the kitchen), improving even more the acoustic comfort for both workers and customers.

The video of this case-study can be seen here.