Sine 1984, simultaneous observations of irradiance and velocity solar acoustic modes, have been carried out by several authors in order to measure the phase difference between irradiance and velocity modes. Following the earliest observations with a stratospheric balloon (Frolich and van Der Raay, 1984), a two ground-based stations (Tenerife and Baja, California) were established (Jimenez et al., 1990) obtaining coherence results in the frequency range from 2.5 mHz to 4.3 mHz. These phase differences between irradiance and velocity solar acoustic modes are interpreted in terms of the non-adiabatic behavior of the solar atmosphere. In 1988 the IPHIR (Frolich et al., 1988) instrument flown on the PHOBOS-2 mission to Mars and measured the solar irradiance during 150 consecutive days. The best velocity observations obtained in Tenerife for this period were compared with IPHIR data to compute the phase differences (Schrijver et al., 1991). The final conclusion is that good agreement is attained between `space', `quasi-space' and `ground observations' which yield a phase diffference of about -125 degrees in the frequency range 2.5 mHz to 4.2 mHz, with a slight increase suggested by the data running up to 4.6 mHz. The entire scientific community looks forward to SOHO data, which will increase a great deal the quality of helioseismology results. Concerning phase differences and gains between intensity and velocity solar oscillations, we will have more raw continuous data (GOLF, VIRGO and MDI) which will improve the accuracy of the results, and we will probably be able to extend the results to low and high frequencies and study `changes' with time. Other important projects before the launch of SOHO are the SOVA experiment (EURECA satellite), which is now in the space and the DIFOS experiment on board the CORONAS satellite which will be launched in autumn 1993. These irradiance data together with ground-based velocity data will offer a good opportunity to improve current results.