This study shows an improvement of the hiding capacity of the Quantization Index Modulation (QIM) method to hide voice signals into audio. The main reason to improvement the hiding capacity of the QIM method is that be feasible apply it in audio steganography, because its hiding capacity low usually is an impediment because can create Stego signals very big and then cause a slow communication because there is a big amount of information on the channel information. The improvement done to QIM method is evaluated by different tests to ensure that the secret information is imperceptible and that the method is transparent from the statistical viewpoint.