Gayarre's voice was slightly guttural and at times could show hardness in the very high notes and an uncertain attack. Nevertheless, it was full, resonant and extraordinarily fascinating. He was distinguished for his breath control, extremely clear diction, vibrant and passionate tone and for his ability to both soften and strengthen that tone. The way he produced contrasts of colour and intensity was incomparable. Yet he sometimes over-used unexpected contrasts of fortissimo and pianissimo and he also seemed to sometimes slow down the tempo excessively. [...] When he sang "La favorita" at La Scala on 2 January 1876, the audience was harsh and indifferent. However, the next day, the critic, Filippi, wrote that the Milanese audience had been present not at the debut of a tenor but at the "consecration of a genius of singing."