Receiving God’s speech from behind a veil or with intermediary of a messenger just belongs to the Apostles. But “revelation” as a direct way of speaking includes the Prophetic revelation and inspiration. God speaks with human and other creatures through inspiration.
The Qur’an states three different modes through which God speaks to a human: “It is not for any human being that God should speak unto him, except by revelation, or from behind a veil, or that He should send a messenger in order to reveal what He will by His Leave. Truly He is Exalted, Wise.” [1] Indeed, God speaks to human directly or with an intermediary. The latter just belongs to the Apostles, but the former has a complex meaning. “Revelation” renders both prophetic revelation, and inspiration which is called in Arabic “Ilham”. The second usage of revelation which means inspiration is granted to saints and even ordinary people. [2] For instance, the Mother of Moses received such a revelation. [3] Also, God revealed unto the bee to take up dwelling among the mountians. [4] Such a inspiration has been also given to the human soul. [5]
[1] Chapter 42, verse 51. وَمَا كَانَ لِبَشَرٍ أَنْ يكَلِّمَهُ اللَّهُ إِلَّا وَحْيا أَوْ مِنْ وَرَاءِ حِجَابٍ أَوْ يرْسِلَ رَسُولًا فَيوحِي بِإِذْنِهِ مَا يشَاءُ إِنَّهُ عَلِي حَكِيمٌ
[2] See: Al-Mizan fi Tafsir Al-Qur’an, v 16 (see the description of the verse 28:7)
[3] Chapter 28, verse 7. وَأَوْحَينَا إِلَى أُمِّ مُوسَى أَنْ أَرْضِعِيهِ فَإِذَا خِفْتِ عَلَيهِ فَأَلْقِيهِ فِي الْيمِّ وَلَا تَخَافِي وَلَا تَحْزَنِي إِنَّا رَادُّوهُ إِلَيكِ وَجَاعِلُوهُ مِنَ الْمُرْسَلِينَ
[4] Chapter 16, verse 68. وَأَوْحَى رَبُّكَ إِلَى النَّحْلِ أَنِ اتَّخِذِي مِنَ الْجِبَالِ بُيوتًا وَمِنَ الشَّجَرِ وَمِمَّا يعْرِشُونَ
[5] Chapter 91, verse 8. فَأَلْهَمَهَا فُجُورَهَا وَتَقْوَاهَا